平狄克微观经济学(第八版)第八章
平狄克第八版课后答案
平狄克第八版课后答案【篇一：平狄克微观经济学课后习题答案-第7-8 章】> 1. 显性成本2. 她自己做其他事时会得到的最高收入3. 多用资本,少用工人4. 完全竞争价格给定, 即斜率不变5. 不意味6. 意味着递增7. avcac mc 递增mc=avc 最低点mc=ac 最低点1.1 形9 . 长期扩展线为把等产量线簇上斜率相同点连起来,此时它改变了斜率10 .规模经济基础是内在经济,针对一种产品范围经济基础是同时生产高度相关的产品.练习题1.avc=1000 ac=1000+1000/q非常大,最后为10002. 不对,除非工人只可以在这里找到工作3. 见书后4. 见书后5. 见书后6. 每个均衡点斜率更小7. 不同意,应按不同时段定价,如不可,则同意8. 见书后9.tc=120000+3000(q/40)+2000ac=75+122000/qmc=75ac 随q 减小2 个劳动组,1600 元1/4, 更大的生产能力11.190 万元53 元53 元19 元第七章附录练习题1 、我们考查规模报酬时可由f( ak，al)与af( k，l)之间的关系判断当f( ak，al) af( k，l),表明是规模报酬递增；当f( ak，al) =af( k，l),表明是规模报酬不变；当f( ak，al) af( k，l),表明是规模报酬递减；( a)规模报酬递增；( b)规模报酬不变；( c)规模报酬递增。
2 、根据已知条件，资本价格r=30 ，设劳动价格为w，则成本函数c=30k+ wl联立(1) ，(2)，(3)可得k=(w/3) 1/2 ,l=(300/w) 1/2 ,此时成本最小，代入成本函数c=30k+ wl ，得c=2 ( 300w ) 1/2联立(1) ，(2)，(3)可得k/l=3/4 ,此时成本最小，即生产既定产出的成本最小化的资本和劳动的组合为资本/劳动=3/4。
4、( a)已知q=10k0.8(l-40)0.2 ,得mpl=2(k/ (l-40))0.8 , mpk=8( (l-40) / k)0.2 ,在最小成本点有：mpl/ mpk=w/r即2(k/ (l-40))0.8/8( (l-40) / k)0.2=w/r ，k/( l-40) =4 w/r ，l-40=kr/4w ，0.80.20.2q=10k(l-40)=10 k ( r/4w)，最小需求为:k=q/10(r/4w)0.2 ，l=40+ q (r/4w)0.8/10总成本函数为：tc=10q+kr+lw=10q+q/10((4w)0.2r0.8+(r/4)0.8w0.2)+40w( b)当r=64 ，w=32 时tc=10q+ (2*20.2+0.50.8)32 q/10+1280tc=1280+10q+91.84 q/10=1280+19.184q该技术呈现规模递减。
平狄克《微观经济学》(第8版)笔记和课后习题详解复习答案
平狄克《微观经济学》（第8版）笔记和课后习题详解完整版>精研学习䋞>无偿试用20％资料全国547所院校视频及题库全收集考研全套>视频资料>课后答案>往年真题>职称考试第1篇导论：市场和价格第1章绪论1.1复习笔记1.2课后复习题详解1.3课后练习题详解第2章供给和需求的基本原理2.1复习笔记2.2课后复习题详解2.3课后练习题详解第2篇生产者、消费者与竞争性市场第3章消费者行为3.1复习笔记3.2课后复习题详解3.3课后练习题详解第4章个人需求和市场需求4.1复习笔记4.2课后复习题详解4.3课后练习题详解第4章附录需求理论——一种数学的处理方法第5章不确定性与消费者行为5.1复习笔记5.2课后复习题详解5.3课后练习题详解第6章生产6.1复习笔记6.2课后复习题详解6.3课后练习题详解第7章生产成本7.1复习笔记7.2课后复习题详解7.3课后练习题详解第7章附录生产与成本理论——一种数学的处理方法第8章利润最大化与竞争性供给8.1复习笔记8.3课后练习题详解第9章竞争性市场分析9.1复习笔记9.2课后复习题详解9.3课后练习题详解第3篇市场结构与竞争策略第10章市场势力：垄断和买方垄断10.1复习笔记10.2课后复习题详解10.3课后练习题详解第11章有市场势力的定价11.1复习笔记11.2课后复习题详解11.3课后练习题详解第11章附录纵向联合厂商第12章垄断竞争和寡头垄断12.1复习笔记12.2课后复习题详解12.3课后练习题详解第13章博弈论与竞争策略13.1复习笔记13.2课后复习题详解13.3课后练习题详解第14章投入要素市场14.1复习笔记14.2课后复习题详解14.3课后练习题详解第15章投资、时间与资本市场15.1复习笔记15.2课后复习题详解15.3课后练习题详解第4篇信息、市场失灵与政府的角色第16章一般均衡与经济效率16.1复习笔记16.2课后复习题详解16.3课后练习题详解第17章信息不对称的市场17.1复习笔记17.2课后复习题详解17.3课后练习题详解第18章外部性和公共物品18.1复习笔记18.2课后复习题详解附录指定平狄克《微观经济学》教材为考研参考书目的院校列表。
平狄克微观经济学全学习教案
会计学
1
第一页，编辑于星期一：二十一点 二十一分。
第一篇 基础知识
第二讲 微观经济学的主要内容
市场：买者和卖者相互作用确定商品价格的系统
地理界限和产品范围
竞争性和非竞争性
价格：买卖商品或服务必须收付的一定量的货币
实际价格和名义价格
消费者价格指数（CPI）
市场价格由买卖双方的相互作用决定产业是提供同类商品的厂商； 套利是从一个地方低价买进而从另一个地方高价卖出；
ΔL）； 乘以边际劳动（
又因为劳动的边际产出（MPL）
Δ Q Δ ＝
消费者通过比较市场篮子来做出选 择
无差异曲线向下第13倾页/共8斜9页 且不与另一条 相交
第十四页，编辑于星期一：二十一点 二十一分 。
第二篇 生产者、
消费者及竞争性市场
第4章 个别需求和市场需求
预算线因价格变化发生偏转时， 可与不同的无差异曲线相切
价格—消费曲线说明了不同价格 条件下的效用最大化
需求曲线：显示其他因素不变时对
既定价格消费者第3页愿/共89页意购买的商品数
量，表示为Q = Q (P)，在图形上， D D
第四页，编辑于星期一：二十一点 二十一分。
第一篇 基础知识
第五讲 市场机制
在使市场出清的均衡价格上供求曲 线相交
特点：Qd=Qs；无短缺；无过剩； 无变动倾向
存在过剩时，生产者降价， Qd增加 Qs减少
数量都是可变的，并且都呈现边际 报酬递减的趋势。
劳动—资本的边际技术替代率 （MRTS）是指在保持产出不变的前
提下，多投入一单位劳动而相应减 少的资本投入的量。
注意：在等产量曲线上边际技术替
代率递减
平狄克经济学8章
CHAPTER 8PROFIT MAXIMIZATION AND COMPETITIVE SUPPLYREVIEW QUESTIONS1. Why would a firm that incurs losses choose to produce rather than shut down?Losses occur when revenues do not cover total costs. If revenues are greater thanvariable costs, but not total costs, the firm is better off producing in the short run ratherthan shutting down, even though it is incurring a loss. The reason is that the firm willbe stuck will all its fixed cost and have no revenue if it shuts down, so its loss will equalits fixed cost. If it continues to produce, however, and revenue is greater than variablecosts, the firm can pay for some of its fixed cost, so its loss is less than it would be if itshut down. In the long run, all costs are variable, and thus all costs must be covered ifthe firm is to remain in business.2. Explain why the industry supply curve is not the longrun industry marginal cost curve.In the short run, a change in the market price induces the profitmaximizing firm tochange its optimal level of output. This optimal output occurs where price is equal tomarginal cost, as long as marginal cost exceeds average variable cost. Therefore, theshortrun supply curve of the firm is its marginal cost curve, above average variable cost.(When the price falls below average variable cost, the firm will shut down.)In the long run, a change in the market price induces entry into or exit from theindustry and may induce existing firms to change their optimal outputs as well. As aresult, the prices firms pay for inputs can change, and these will cause the firms’marginal costs to shift up or down. So longrun supply is not the sum of the existingfirms’ longrun marginal cost curves. The longrun supply curve depends on the numberof firms in the market and on how their costs change due to any changes in input costs.As a simple example, consider a constantcost industry where each firm has a UshapedLAC curve. Here the input prices do not change, only the number of firms changeswhen industry price changes. Each firm has an increasing LMC, but the industry longrun supply is horizontal because any change in industry output comes about by firmsentering or leaving the industry, not by existing firms moving up or down their LMCcurves.3. In longrun equilibrium, all firms in the industry earn zero economic profit. Why is this true?The theory of perfect competition explicitly assumes that there are no entry or exitbarriers to new participants in an industry. With free entry, positive economic profitsinduce new entrants. As these firms enter, the supply curve shifts to the right, causinga fall in the equilibrium price of the product. Entry will stop, and equilibrium will beachieved, when economic profits have fallen to zero.Some firms may earn greater accounting profits than others because, for example, theyown a superior source of an important input, but their economic profits will be the same.To be more concrete, suppose one firm can mine a critical input for $2 per pound whileall other firms in the industry have to pay $3 per pound. The one firm will have anaccounting cost advantage and will report higher accounting profits than other firms inthe industry. But there is an opportunity cost associated with the company’s input use,because other firms would be willing to pay up to $3 per pound to buy the input from119Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall.the firm with the superior mine. Therefore, the company should include a $1 per poundopportunity cost for using its own input rather than selling it to other firms. Then, thatfirm’s economic costs and economic profit will be the same as all the other firms in theindustry. So all firms will earn zero economic profit in the long run.4. What is the difference between economic profit and producer surplus?Economic profit is the difference between total revenue and total cost. Producer surplusis the difference between total revenue and total variable cost. So fixed cost issubtracted to find profit but not producer surplus, and thus profit equals producersurplus minus fixed cost (or producer surplus equals profit plus fixed cost).5. Why do firms enter an industry when they know that in the long run economic profit will be zero?Firms enter an industry when they expect to earn economic profit, even if the profit willbe shortlived. These shortrun economic profits are enough to encourage entry becausethere is no cost to entering the industry, and some economic profit is better than none.Zero economic profit in the long run implies normal returns to the factors of production,including the labor and capital of the owner of the firm. So even when economic profitfalls to zero, the firm will be doing as well as it could in any other industry, and then theowner will be indifferent between staying in the industry or exiting.6. At the beginning of the twentieth century, there were many small American automobile manufacturers. At the end of the century, there were only three large ones. Suppose that this situation is not the result of lax federal enforcement of antimonopoly laws. How do you explain the decrease in the number of manufacturers? (Hint: What is the inherent cost structure of the automobile industry?)Automobile plants are highly capitalintensive, and consequently there are substantialeconomies of scale in production. So, over time, the automobile companies thatproduced larger quantities of cars were able to produce at lower average cost. They thensold their cars for less and eventually drove smaller (higher cost) companies out ofbusiness, or bought them to become even larger and more efficient. At very large levelsof production, the economies of scale diminish, and diseconomies of scale may even occur.This would explain why more than one manufacturer remains.7. Because industry X is characterized by perfect competition, every firm in the industry is earning zero economic profit. If the product price falls, no firms can survive. Do you agree or disagree? Discuss.Disagree. If the market price falls, all firms will suffer economic losses. They will cutproduction in the short run but continue in business as long as price is above averagevariable cost. In the long run, however, if price stays below average total cost, somefirms will exit the industry. As firms leave industry X, the market supply decreases (i.e.,shifts to the left). This causes the market price to increase. Eventually enough firmsexit so that price increases to the point where profits return to zero for those firms stillin the industry, and those firms will continue to survive and produce product X.8. An increase in the demand for video films also increases the salaries of actors and actresses. Is the longrun supply curve for films likely to be horizontal or upward sloping? Explain.The longrun supply curve depends on the cost structure of the industry. If there is arelatively fixed supply of actors and actresses, as more films are produced, highersalaries must be offered. Therefore, the industry experiences increasing costs. In anincreasingcost industry, the longrun supply curve is upward sloping. Thus, the supplycurve for films would be upward sloping.120Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall.Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall.1219. True or false: A firm should always produce at an output at which longrun average cost is minimized. Explain.False. In the long run, under perfect competition, firms will produce where long run average cost is minimized. In the short run, however, it may be optimal to produce ata different level. For example, if price is above the longrun equilibrium price, the firmwill maximize shortrun profit by producing a greater amount of output than the level atwhich LAC is minimized as illustrated in the diagram. P L is the longrun equilibrium price, and q L is the output level that minimizesLAC. If price increases to P ¢ in the short run,the firm maximizes profit by producing q ¢,which is greater than q L , because that is the output level at which SMC (shortrun marginal cost) equals price.10. Can there be constant returns to scale in an industry with an upwardsloping supply curve? Explain.Yes. Constant returns to scale means that proportional increases in all inputs yield the same proportional increase in output. However, when all firms increase their input use, the prices of some inputs may rise because their supply curves are upward sloping. For example, production that uses rare or depleting inputs will see higher input costs as production increases. Doubling inputs will still yield double output, but because of rising input prices, production costs will more than double. In this case the industry is an increasingcost industry, and it will have an upwardsloping supply curve. Therefore, an industry can have both constant returns to scale and an upwardsloping industry supply curve.11. What assumptions are necessary for a market to be perfectly competitive? In light of what you have learned in this chapter, why is each of these assumptions important?The three primary assumptions of perfect competition are (1) all firms in the industry are price takers, (2) all firms produce identical products, and (3) there is free entry and exit of firms to and from the market. The first two assumptions are important because they imply that no firm has any market power and that each faces a horizontal demand curve. As a result, firms produce where price equals marginal cost, which defines their supply curves. With free entry and exit, positive (negative) economic profits encourage firms to enter (exit) the industry. Entry and exit affects industry supply and price. In the long run, entry or exit continues until price equals longrun average cost and firms earn zero economic profit.12. Suppose a competitive industry faces an increase in demand (i.e., the demand curve shifts upward). What are the steps by which a competitive market insures increased output? Will your answer change if the government imposes a price ceiling?If demand increases, price and profits increase. The price increase causes existing firms to increase output, and the positive profits induce new firms to enter the industry in the long run, shifting the supply curve to the right. This results in a new equilibrium with a higher quantity and a reduced price that earns all firms zero economic profit. With an effective price ceiling, price will not increase when demand increases, and firms willPrice Output LACSMC P LP ¢ q L q ¢ SACtherefore not increase output. Also, without an increase in economic profit, no newfirms enter, and there is no shift in the supply curve. So the result is very different witha price ceiling. Output does not increase as a result of the increase in demand. Insteadthere is a shortage of the product.13. The government passes a law that allows a substantial subsidy for every acre of land used to grow tobacco. How does this program affect the longrun supply curve for tobacco?A subsidy on land used to grow tobacco decreases every farmer’s average cost ofproducing tobacco and will lead existing tobacco growers to increase output. Inaddition, tobacco farmers will make positive economic profits that will encourageother firms to enter tobacco production. The result is that both the shortrun andlongrun supply curves for the industry will shift down and to the right14. A certain brand of vacuum cleaners can be purchased from several local stores as well as from several catalogue or website sources.a. If all sellers charge the same price for the vacuum cleaner, will they all earn zeroeconomic profit in the long run?Yes, all earn zero economic profit in the long run. If economic profit were greaterthan zero for, say, online sources, then firms would enter the online industry andeventually drive economic profit for online sources to zero. If economic profit werenegative for catalogue sellers, some catalogue firms would exit the industry untileconomic profit returned to zero. So all must earn zero economic profit in the longrun. Anything else will generate entry or exit until economic profit returns to zero.b. If all sellers charge the same price and one local seller owns the building in whichhe does business, paying no rent, is this seller earning a positive economic profit?No this seller would still earn zero economic profit. If he pays no rent then theaccounting cost of using the building is zero, but there is still an opportunity cost,which represents the value of the best alternative use of the building.c. Does the seller who pays no rent have an incentive to lower the price he chargesfor the vacuum cleaner?No, he has no incentive to charge a lower price because he can sell as many units ashe wants at the current market price.Lowering his price will only reduce his economic profit. Since all firms sell theidentical good, they will all charge the same price for that good.EXERCISES1. The data in the table on page 307 give information about the price (in dollars) for which a firm can sell a unit of output and the total cost of production.a. Fill in the blanks in the table.b. Show what happens to the firm’s output choice and profit if the price of the productfalls from$60 to $50.qPRP = 60CpP = 60MCP = 60MRP = 60RP = 50MRP = 50pP = 500 60 1001001 60 1502 60 1783 60 198Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall.1224 60 2125 60 2306 60 2507 60 2728 60 3109 60 35510 60 41011 60 475The table below shows the firm’s revenue and cost for the two prices.q PRP= 60CpP= 60MCP = 60MRP= 60RP= 50MRP= 50pP= 500 60 0 100 100 ___ ___ 0 ___ 1001 60 60 150 90 50 60 50 50 1002 60 120 178 58 28 60 100 50 783 60 180 198 18 20 60 150 50 484 60 240 212 28 14 60 200 50 125 60 300 230 70 18 60 250 50 206 60 360 250 110 20 60 300 50 507 60 420 272 148 22 60 350 50 788 60 480 310 170 38 60 400 50 909 60 540 355 185 45 60 450 50 9510 60 600 410 190 55 60 500 50 9011 60 660 475 185 65 60 550 50 75At a price of $60, the firm should produce ten units of output to maximize profit, whichis $190 when q = 10. This is also the point closest to where price equals marginal costwithout having marginal cost exceed price. At a price of $50, the firm should producenine units to maximize profit, which will be $95. Thus, when price falls from $60 to $50,the firm’s output drops from 10 to 9 units and profit falls from $190 to $95.2. Using the data in the table, show what happens to the firm’s output choice and profit if the fixed cost of production increases from $100 to $150 and then to $200. Assume that the price of the output remains at $60 per unit. What general conclusion can you reach about the effects of fixed costs on the firm’s output choice?The table below shows the firm’s revenue and cost information for fixed cost (F ) of $100,$150, and $200.In all three cases, with fixed cost equal to 100, then 150, and then 200, the firm willproduce 10 units of output because this is the point closest to where price equalsmarginal cost without having marginal cost exceed price. Fixed costs do not influencethe optimal quantity, because they do not influence marginal cost. Higher fixed costsresult in lower profits, but the highest profit always occurs at the same level of output,which is 10 units in this example.Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall.123q P RCF= 100pF= 100MCCF= 150pF= 150CF= 200pF= 2000 60 0 100 100 ___ 150 150 200 2001 60 60 150 90 50 200 140 250 1902 60 120 178 58 28 228 108 278 1583 60 180 198 18 20 248 68 298 1184 60 240 212 28 14 262 22 312 725 60 300 230 70 18 280 20 330 306 60 360 250 110 20 300 60 350 107 60 420 272 148 22 322 98 372 488 60 480 310 170 38 360 120 410 709 60 540 355 185 45 405 135 455 8510 60 600 410 190 55 460 140 510 9011 60 660 475 185 65 525 135 575 853. Use the same information as in Exercise 1.a. Derive the firm’s shortrun supply curve. (Hint: you may want to plot theappropriate cost curves.)The firm’s shortrun supply curve is its marginal cost curve above average variable cost.The table below lists marginal cost, total cost, variable cost, fixed cost, and averagevariable cost. The firm will produce 8 or more units depending on the market price andwill not produce in the 0 – 7 units of output range because in this range MC is less thanAVC. When MC is below AVC, the firm minimizes losses by shutting down andproducing nothing in the short run.Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall.124Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall.125Q C MC TVC TFC AVC 0 100 100 ___ 0 100 ___ 1 150 50 50 100 50.0 2 178 28 78 100 39.0 3 198 20 98 100 32.7 4 212 14 112 100 28.0 5 230 18 130 100 26.0 6 250 20 150 100 25.0 7 272 22 172 100 24.6 8 310 38 210 100 26.3 9 355 45 255 100 28.3 10 410 55 310 100 31.0 114756537510034.1b. If 100 identical firms are in the market, what is the industry supply curve?For 100 firms with identical cost structures, the market supply curve is the horizontalsummation of each firm’s output at each price. From the table above we know that when P = 38, each firm will produce 8 units, because MC = 38 at an output of 8 units. Therefore, when P = 38, Q = 800 units would be supplied by all the firms in the industry. The other points we know are: P = 45 and Q = 900,P = 55 and Q = 1000, and P = 65 and Q = 1100. The industry supply curve is shown in the diagram below.80038QPS9001000110045 55 654. Suppose you are the manager of a watchmaking firm operating in a competitive market. Your cost of production is given by C = 200 + 2q 2 , where q is the level of output and C is total cost. (The marginal cost of production is 4q; the fixed cost is $200.)a. If the price of watches is $100, how many watches should you produce to maximizeprofit?Profits are maximized where price equals marginal cost. Therefore,100 = 4q, or q = 25.b. What will the profit level be?Profit is equal to total revenue minus total cost:p= Pq – (200 + 2q 2). Thus,p = (100)(25) – (200 + 2(25) 2 ) = $1050.c. At what minimum price will the firm produce a positive output?A firm will produce in the short run if its revenues are greater than its total variablecosts. The firm’s shortrun supply curve is its MC curve above minimum AVC. Here,AVC = VCq=2q 2q=2q. Also, MC = 4q. So, MC is greater than AVC for any quantitygreater than 0. This means that the firm produces in the short run as long as price ispositive.5. Suppose that a competitive firm’s marginal cost of producing output q is given by MC(q) = 3 + 2q. Assume that the market price of the firm’s product is $9.a. What level of output will the firm produce?The firm should set the market price equal to marginal cost to maximize its profits:9 = 3 + 2q, or q = 3.Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall.126Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall.127b. What is the firm’s producer surplus?Producer surplus is equal to the area below the market price, i.e., $9.00, and above the marginal cost curve, i.e., 3 + 2q . Because MC is linear, producer surplus is a triangle with a base equal to 3 (since q = 3) and a height of $6 (since 9 – 3 = 6). The area of a triangle is (1/2)(base)(height). Therefore, producer surplus is (0.5)(3)(6) = $9.PriceQuantity12 3 4 5 6 7 8 9 10 1234MC (q ) = 3 + 2qProducer’s SurplusP = $9.00Producer Surplus c. Suppose that the average variable cost of the firm is given by AVC(q ) = 3 + q . Supposethat the firm’s fixed costs are known to be $3. Will the firm be earning a positive, negative, or zero profit in the short run?Profit is equal to total revenue minus total cost. Total cost is equal to total variable cost plus fixed cost. Total variable cost is equal to [AVC (q )]q . Therefore, at q = 3, AVC (q ) = 3 + 3 = 6, and thereforeTVC = (6)(3) = $18.Fixed cost is equal to $3. Therefore, total cost equals TVC plus TFC , orC = $18 + 3 = $21.Total revenue is price times quantity:R = ($9)(3) = $27.Profit is total revenue minus total cost:p = $27 – 21 = $6.Therefore, the firm is earning positive economic profits. More easily, you might recall that profit equals producer surplus minus fixed cost. Since we found that producer surplus was $9 in part (b), profit equals 9 – 3 or $6.6. A firm produces a product in a competitive industry and has a total cost function C = 50 + 4q + 2q 2and a marginal cost function MC = 4 + 4q. At the given market price of $20, the firm is producing 5 units of output. Is the firm maximizing its profit? What quantity of output should the firm produce in the long run?If the firm is maximizing profit, then price will be equal to marginal cost.P =MCresults in 20 = 4 + 4q, or q = 4. The firm is not maximizing profit; it is producing toomuch output. The current level of profit isp = Pq – C = 20(5) – (50 + 4(5) + 2(5) 2 ) = –20,and the profit maximizing level isp = 20(4) – (50 + 4(4) + 2(4) 2 ) = –18.Given no change in the price of the product or the cost structure of the firm, the firmshould produce q = 0 units of output in the long run since economic profit is negativeat the quantity where price equals marginal cost. The firm should exit the industry.7. Suppose the same firm’s cost function is C(q) = 4q 2+ 16.a. Find variable cost, fixed cost, average cost, average variable cost, and averagefixed cost. (Hint: Marginal cost is given by MC = 8q.)Variable cost is that part of total cost that depends on q (so VC =4q 2 ) and fixed costis that part of total cost that does not depend on q (FC = 16).VC = 4q 2FC =16AC= C(q)q= 4q +16qAVC = VCq= 4qAFC = FCq=16qCopyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall.128Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall. 129b. Show the average cost, marginal cost, and average variable cost curves on a graph.Average cost is Ushaped.Average cost is relativelylarge at first because thefirm is not able to spread thefixed cost over very manyunits of output. As outputincreases, average fixed costfalls quickly, leading to arapid decline in average cost.Average cost will increase atsome point because theaverage fixed cost willbecome very small andaverage variable cost isincreasing as q increases.MC and AVC are linear inthis example, and both passthrough the origin. Average variable cost is everywhere below average cost. Marginal cost iseverywhere above averagevariable cost. If the average is rising, then the marginalmust be above the average.Marginal cost intersects average cost at its minimum point, which occurs at aquantity of 2 where MC and AC both equal $16.c. Find the output that minimizes average cost.Minimum average cost occurs at the quantity where MC is equal to AC:AC = 4q + 16 q=8q = MC 16 q= 4q 16 = 4q2 4 =q 22 =q .d. At what range of prices will the firm produce a positive output?The firm will supply positive levels of output in the short run as long as P = MC >AVC, or as long as the firm is covering its variable costs of production. In this case,marginal cost is above average variable cost at all output levels, so the firm willsupply positive output at any positive price.e. At what range of prices will the firm earn a negative profit?The firm will earn negative profit when P = MC < AC, or at any price belowminimum average cost. In part (c) above we found that the minimum average costoccurs where q = 2. Plug q = 2 into the average cost function to find AC = 16. Thefirm will therefore earn negative profit if price is below 16. Average and Marginal Costs 0 4 8 1216 20 24 28 32 36 40 44 48 0 1 2 3 4 5 6 Quantity Cost MC AC AVCCopyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall. 130f. At what range of prices will the firm earn a positive profit?In part (e) we found that the firm would earn negative profit at any price below 16.The firm therefore earns positive profit as long as price is above 16.8. A competitive firm has the following shortrun cost function:C (q ) = q 3 -8q 2 +30q +5.a. Find MC, AC, and AVC and sketch them on a graph.The functions can be calculated as follows:. 30 8 5 30 8 30 16 3 2 2 2 + - = = + + - = = + - = = q q q VC AVC qq q q C AC q q dqdC MC Graphically, all three cost functions are Ushaped in that cost initially declines as q increases, and then increases as q increases. Average variable cost is below average cost everywhere. Marginal cost is initially below AVC and then increases to intersect AVC at its minimum point. MC is also initially below AC and then intersects AC at itsminimum point. b. At what range of prices will the firm supply zero output?The firm will find it profitable to produce in the short run as long as price is greaterthan or equal to average variable cost. If price is less than average variable cost thenthe firm will be better off shutting down in the short run, as it will only lose its fixedcost and not fixed cost plus some variable cost. Here we need to find the minimumaverage variable cost, which can be done in two different ways. You can either setmarginal cost equal to average variable cost, or you can differentiate averagevariable cost with respect to q and set this equal to zero. In both cases, you can solvefor q and then plug into AVC to find the minimum AVC. Here we will set AVC equalto MC:AVC =q 2 -8q +30 = 3q 2 -16q + 30= MC2q 2 = 8qq = 4AVC (q = 4)= 4 2 -8*4 + 30=14.Hence, the firm supplies zero output if P < $14. Average and Marginal Costs 04812162024283236404448 52 0 1 2 3 4 5 6 7QuantityCost MC AC AVC S Shortrun supply curveCopyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall. 131c. Identify the firm’s supply curve on your graph.The firm’s supply curve is the MC curve above the point where MC = AVC. The firmwill produce at the point where price equals MC as long as MC is greater than orequal to AVC. This point is labeled S on the graph, so the shortrun supply curve isthe portion of MC that lies above point S.d. At what price would the firm supply exactly 6 units of output?The firm maximizes profit by choosing the level of output such that P = MC. To findthe price where the firm would supply 6 units of output, set q equal to 6 and solve forMC:P = MC = 3q 2 -16q + 30= 3(6 2)-16(6) +30 = 42.9. a. Suppose that a firm’s production function is q = 9x 1 2 in the short run, where there are fixed costs of $1000, and x is the variable input whose cost is $4000 per unit. What is the total cost of producing a level of output q? In other words, identify the total cost function C(q).Since the variable input costs $4000 per unit, total variable cost is 4000 times thenumber of units used, or 4000x. Therefore, the total cost of the inputs used is C(x) =variable cost + fixed cost = 4000x + 1000. Now rewrite the production function toexpress x in terms of q: x = q 281. We can then substitute this into the above cost function to find C(q): C (q ) = 4000q 281+1000. b. Write down the equation for the supply curve.The firm supplies output where P = MC as long as MC ≥ AVC . In this example, MC =98.7654q is always greater than AVC = 49.3827q , so the entire marginal cost curve isthe supply curve. Therefore P = 98.7654q , or q = .010125P , is the firm’s shortrunsupply curve.c. If price is $1000, how many units will the firm produce? What is the level of profit?Illustrate on a cost curve graph.Use the supply curve from part b: q = .010125(1000) = 10.125.Profit is 1000(10.125) – [(4000(10.125) 2 /81) + 1000] = $4,062.50. Graphically, thefirm produces where the price line hits the MC curve. Since profit is positive, thisoccurs at a quantity where price is greater than average cost. To find profit on thegraph, take the difference between the revenue rectangle (price times quantity) andthe cost rectangle (average cost times quantity). The area of the resulting rectangleis the firm’s profit.。
《微观经济学》平狄克 第8章课件
Chapter 8
4
▪ 根据上述四点，微观经济学中的市场被划分为四个 类型 完全竞争市场 垄断竞争市场 寡头市场 垄断市场
Chapter 8
5
表1 市场分类及其特点
市场和厂商 的类型 完全竞争 Perfect competition 垄断竞争
寡头 Oligopoly 垄断 Monopoly
厂商 数目 很多
很多 几个 一个
产品差别的 对价格的控 进出一个行业 接近哪种市
程度
制程度
的难易程度 场情况
完全无差别 没有
很容易
一些农产品
有差别
有一些
比较容易
香烟、糖果、
日用品
▪ 一、市场的类型
商品市场 产品市场 劳务市场
生产要素市场 土地市场 资本市场 劳动力市场 经理市场
Chapter 8
3
1、不同市场类型会导致企业的经济行为有所差异， 要研究企业行为必须在不同市场类型下进行分析。
2、市场竞争程度的强弱是微观经济学划分市场类型 的标准。
影响市场竞争程度强弱的具体因素：
➢ 较高的价格可以弥补厂商因产量的增加而产生的较高 的生产成本，并提高总利润。因此，这个较高的价格 适用于所有的商品。
Chapter 8
50
8.4 竞争性厂商的短期供给曲线
▪ 厂商对投入品价格变动的反应
➢ 当产品的价格发生变动时，厂商往往会改变产 量水平，以使生产的边际成本与价格保持相等。
➢ 下面我们来分析当一种投入品的价格发生变动 时，厂商如何选择产量。
微观经济学平狄克第八版课后答案
微观经济学平狄克第八版课后答案【篇一：平狄克《微观经济学》课后答案 (中文版) 1-3章】> 1．市场是通过相互作用决定一种或一系列产品价格的买卖双方的集合，因此可以把市场看作决定价格的场所。
行业是出售相同的或紧密相关的产品的厂商的集合，一个市场可以包括许多行业。
2．评价一个理论有两个步骤：首先，需要检验这个理论假设的合理性；第二，把该理论的预测和事实相比较以此来验证它。
如果一个理论无法被检验的话，它将不会被接受。
因此，它对我们理解现实情况没有任何帮助。
3．实证分析解释“是什么”的问题，而规范分析解释的是“应该是什么”的问题。
对供给的限制将改变市场的均衡。
a中包括两种分析，批评这是一种“失败的政策”——是规范分析，批评其破坏了市场的竞争性——是实证分析。
b向我们说明在燃油的配给制下总社会福利的被损坏——是实证分析。
4．由于两个市场在空间上是分离的，商品在两地间的运输是套利实现的条件。
如果运输成本为零，则可以在oklahoma购买汽油，到new jersey出售，赚取差价；如果这个差价无法弥补运输成本则不存在套利机会。
5．商品和服务的数量与价格由供求关系决定。
鸡蛋的实际价格从1970年至1985年的下降，一方面是由于人们健康意识的提高而导致鸡蛋需求的减少，同时也因为生产成本的降低。
在这两种因素下，鸡蛋的价格下降了。
大学教育的实际价格的升高，是由于越来越多的人倾向于获得大学教育而导致需求提高，同时教育的成本也在升高。
在这两方面因素作用下，大学教育费用提高了。
6．日圆相对美圆来说，价值升高，升值前相比，兑换同样数量的日圆需要付出更多的美圆。
由汇率的变化引起购买力的变化，在日本市场出售的美国汽车，由于美圆贬值日圆升值，持有日圆的消费者将较以前支付较底的价格；而在美国市场出售的日本汽车，由于日圆升值美圆贬值，持有美圆的消费者将面对较以前提高的价格。
4.长期弹性和短期弹性区别在于消费者对价格变化的反映速度以及可获得的替代品。
《微观经济学第八章》PPT课件
所以要素成本 MFC = MC MP
边际要素成本曲线和要素供给曲线 MFC
MFC
W(L)
a
0
L
买方垄断厂商的要素使用原则
买方垄断厂商使用要素的边际收益和边际成本分 别等于要素的边际产品价值和边际要素成本。因此， 买方垄断厂商的要素使用原则可以写成：
VMP = MFC
W
MFC
E
W（L）
W1
W0
卖方垄断的收益是要素的复合函数，即R=R[Q（L]，根据
复合函数求导法则即有：
dR dL
=
dR dQ
dQ dL
在卖方垄断条件下，厂商使用要素的边际收益等于产品的 边际收益MR和要素的边际产品MP的乘积MR•MP。这个乘积通常
被称作要素的边际收益产品，并用MRP来表示，即：
MRP = MR • MP
由于买方垄断厂商在产品市场上是完全竞争者， 故其产品的边际收益与产品价格相等：MR=P，从而 其使用要素的边际收益就等于要素的边际产品价值： VMP=P•MP。但是其使用要素的边际成本不等于要素 价格。
买方垄断厂商使用要素的成本和边际成本分析
边际要素成本（MFC）——是增加一单位要素使用所增
加的成本。
完全竞争厂商使用要素的原则可以表示为： VMP = W 或者 MP·P = W
可以用数学方法推导上述要素使用原则。 假设代表完全竞争厂商的利润，它是要素L的函数，则由 利润的定义可有：
π（L）= P·Q（L）- W·L 为了达到利润最大化，必须使
dπdL（L）= P
dQ（L） dL
-
W
=
0
即P
dQ（L） dL
Y
W
PEP K2 K1 K0
平狄克《微观经济学》第八版笔记
《微观经济学》学问点总结第一章绪论微观经济学争论个体经济单位的行为，包括消费者、工人、投资者、土地全部者、企业，事实上包括任何参与经济运行的个人和法人。
宏观经济学争论经济总量，诸如国民产出的水平和增长率、利率、失业以及通货膨胀。
微观经济学就是关于有限性的，争论如何配置稀缺资源。
重要概念包括权衡取舍，价格等。
微观经济学既关注实证问题，也关注标准问题。
实证问题主要是解释和推想，而标准问题关注的是“应当如何”引号的问题。
独立的经济单位按功能可分为买者和卖者。
市场是买者和卖者的集合，通过他们实际或潜在的相互作用来打算一种或多种商品的价格。
行业是指出售一样或严密相关产品的厂商的集合。
套利是指在一个地方低价买进，然后在另一个地方高价卖出的行为。
完全竞争市场，即有很多买者和卖者的市场，没有任何买者和卖者能够影响价格。
卡特尔是指集体行动的生产者群体。
市场价格，竞争性市场中通行的价格。
市场范围，市场的边界，既包括地理的边界，又包括就产品范围而言的边界。
名义价格，未经通货膨胀调整确实定价格。
实际价格，一种依据总体价格指标衡量的价格，这是经过通胀调整后的价格。
消费者价格指数，CPI，衡量总体价格水平的指标。
生产者价格指数，PPI，衡量半成品和批发品的总体价格水平的指标。
其次章供给和需求的根本原理供给曲线，描绘生产者情愿出售的商品数量与该商品价格之间关系的曲线。
供给的变动表示供给曲线的移动，供给量的变动表示沿着供给曲线的移动。
需求曲线，消费者情愿购置的商品数量与该商品价格之间的关系。
需求的变动表示需求曲线的移动，需求量的变动表示沿着需求曲线的移动。
替代品，一种商品的价格上升会导致另一种商品的需求量增加的两种商品。
互补品，一种商品的价格上升会导致另一种商品的需求量下降的两种商品。
均衡或市场出清价格，供给和需求相等时的价格。
市场机制，自由市场中价格不断变动直到市场出清的趋势。
过剩，供给大于需求的情形。
短缺，需求量大于供给量的情形。
平狄克微观经济学(一-十一 章)案例分析
微观经济学第一章案例分析亚当.斯密的悖论在1776年的《国富论》中，亚当·斯密断言：当人们尽量为自己获得更多的物质利益，并且这样做不受阻碍时，他们最终共同使社会受益，即使那不是他们的目的。
这是怎么一回事呢？这是亚当·斯密（1723～1790）在《国富论》中提出的重要论题。
亚当·斯密写道："个体生产者只想达到自己的目标，他这样做时，像其他许多情况下一样，由一只看不见的手引导他去促进一种结果出现，而这个结果并不是他所追求的东西。
"亚当·斯密悖论一直是经济学的核心矛盾，200多年来它一直推动着经济学的发展。
这一理论的效力不断受到宗教权威、经济学之外的理论思想家和经济学家自身的挑战。
虽然如此，"看不见的手"这一悖论使人类行为合理化，且在20世纪越来越多地指导西方甚至非西方国家的经济和政治生活。
另外，斯密更一般的见解，即总体收益的结果也许有别于创造收益的个体意向，已经被诺贝尔奖获得者、经济学家肯尼斯·阿罗称为"使经济思想注入对社会进程一般理解的最重要、最具智慧的贡献"。
这个重要的极具智慧的想法是正确的吗？亚当·斯密与其他启蒙思想家（17世纪后期到18世纪后期）一道尝试着将人们从教会教条束缚和诸如骄傲、嫉妒之类的情感中解放出来，而这些在历史上曾使人类行为被扭曲。
通过强调无私和来世相对于世俗生活的重要性，教会教义遏制了人类状况的暂时进步。
僧侣们看到了社会底层和普通的人们为这种需要被束缚的情感左右。
斯密相信，教会教义也维系一个上流社会，而该社会无助于商业活动。
使牧师和其他人忧心的激情除傲慢和嫉妒外还包括愤怒，以及对荣誉或报复的欲望。
他们的担忧是有根据的，因为历史上这种激情已经导致损坏政治经济稳定的争战杀伐。
自从中世纪以来，商业活动就遭受僧侣和智者们的诋毁，但却受到下等人的推崇，并且这种态度在欧洲创国阶段广为流传。
平狄克：微观经济学8 applications_taxation
Copyright © 2004 South-Western/Thomson Learning
How a Tax Affects Market Participants
• Tax Revenue
• T = the size of the tax • Q = the quantity of the good sold
• Buyers and sellers receive benefits from taking part in the market. • The equilibrium in a market maximizes the total welfare of buyers and sellers.
Copyright © 2004 South-Western/Thomson Learning
Deadweight Losses and the Gains from Trade
• Taxes cause deadweight losses because they prevent buyers and sellers from realizing some of the gains from trade.
Copyright © 2004 South-Western/Thomson Learning
DEADWEIGHT LOSS AND TAX REVENUE AS TAXES VARY
• The Deadweight Loss Debate
• Some economists argue that labor taxes are highly distorting and believe that labor supply is more elastic. • Some examples of workers who may respond more to incentives:
微观经济学总结(平狄克)
第一章绪论经济学的两个主要分支：微观经济学和宏观经济学微观经济学：经济学的分支，主要研究个体经济单位——消费者、厂商、工人和投资者的行为——以及由这些个体组成的市场本身的行为微观经济学还特别关注经济个体之间怎样通过互动形成更大的经济单位——市场和行业宏观经济学：经济学的分支，主要研究总量经济指标，诸如国民产出的水平和增长率、利率、失业以及通货膨胀微观经济学是关于如何配置稀缺资源的学科微观经济学的主题有权衡取舍、价格的作用和决定机制、市场的核心作用、理论和模型实证分析：描述因果关系的分析（客观）规范分析：解析“应该如何”一类问题的分析（主观）市场：买方和卖方的集合，通过他们实际或潜在的相互作用来决定一种或多种商品的价格市场界定：确定一个具体的市场应包括哪些买者、卖者以及产品范围套利：在一个地方低价买进，然后在另一个地方高价卖出的行为完全竞争市场：有许多买者和卖者的市场，没有任何买者或卖者能够影响价格市场价格：竞争性市场中通行的价格市场范围：市场的边界，既包括地理的边界，又包括就产品范围而言的边界名义价格：未经通货膨胀调整的绝对价格实际价格：一种按照总体价格指标衡量的价格，就是通过膨胀调整后的价格实际分析中，我们应该利用消费者价格指数或生产者价格指数把名义价格转换成实际价格消费者价格指数（Consumer Price Index, CPI）：衡量总体价格水平的指标生产者价格指数(Producer Price Index, PPI)：衡量半成品和批发品的总体价格水平的指标名义价格实际价格膨胀前膨胀后章节练习：1、人们常说，一个好的理论是可以用实证的、数据导向的研究来加以证伪的。
试解释为什么一个不能用经验事实来验证的理论不是一个好理论。
2、下面两个陈述哪个是实证分析，哪个是规范分析？这两类分析有什么不同？A、汽油配给制（为个人每年购买的汽油量设置一个最大限额）是一个糟糕的社会政策，因为它阻碍了竞争性市场体系的运转。
平狄克《微观经济学》课后答案 7-8
CHAPTER 7THE COST OF PRODUCTIONIn this chapter, it is easy for the students to concentrate too much on definitions and geometry and lose focus on the economics. Therefore, keep in mind the key concepts: opportunity cost, short-run average and marginal cost, cost minimization, and long-run average cost. These concepts can be illuminated with the supplementary material provided at the end of the chapter, which includes sections on economies of scope, learning curves, and estimating and predicting costs. The Appendix presents the calculus of constrained optimization, as applied to cost minimization. All exercises involve some algebra or geometry: Exercises (12) and (13) are time consuming, but rewarding.Opportunity cost is the conceptual base of this chapter. While most students think of costs in accounting terms, they must develop an understanding of the distinction between accounting, economic, and opportunity costs. One source of confusion is the opportunity cost of capital, i.e., why the rental rate on capital must be considered explicitly by economists. It is important, for example, to distinguish between the purchase price of capital equipment and the opportunity cost of using the equipment. The opportunity cost of a person’s tim e also leads to some confusion for students.Following the discussion of opportunity cost, the chapter diverges in two directions: one path introduces types of cost and cost curves, and the other focuses on cost minimization. Both directions converge with the discussion of long-run average cost.The geometry of total, fixed, variable, average, and marginal costs can prove to be tedious. An emphasis on the following issues helps students master this topic: 1) the relationship between the production function, diminishing returns in the short run, input prices, and the shapes of the various cost curves; 2) the distinction between total, average, and marginal; and 3) the reasonableness of the assumption of constant input prices (note that this assumption w ill be relaxed in Chapter 10’s discussion of monopsony). The determination of the cost-minimizing quantity is crucial to understanding Chapters 8 and 10. The concept of duality (minimizing cost subject to a given level of production) is equivalent to maximizing output subject to a given level of total cost) clarifies this concept for students.A clear understanding of short-run cost and cost minimization is necessary for the derivation of long-run average cost. With long-run costs, stress that firms are operating on short-run cost curves at each level of the fixed factor and that long-run costs do not exist separately from short-run costs. Exercise (6) illustrates the relationship between long-run cost and cost minimization, with an emphasis on the importance of the expansion path. Stress the connection between the shape of a long-run cost curve and returns to scale. While Section 7.7 is starred, it does not require calculus. Example 7.5 “Cost Functions for Electric Power,” gives students another vie w of long-run average cost and allows for discussion of minimum efficient scale, an important determinant of industry structure.1. A firms pays its accountant an annual retainer of $10,000. Is this an explicit or implicit cost?Explicit costs are actual outlays. They include all costs that involve a monetary transaction.An implicit cost is an economic cost that does not necessarily involve a monetary transaction, butstill involves the use of resources. When a firm pays an annual retainer of $10,000, there is amonetary transaction. The accountant trades his or her time in return for money. Therefore,an annual retainer is an explicit cost.2. The owner of a small retail store does her own accounting work. How would you measure the opportunity cost of her work?Opportunity costs are measured by comparing the use of a resource with its alternative uses.The opportunity cost of doing accounting work is the time not spent in other ways, i.e., time suchas running a small business or participating in leisure activity. The economic cost of doingaccounting work is measured by computing the monetary amount that the time would be worth inits next best use.3. Suppose a chair manufacturer finds that the marginal rate of technical substitution of capital for labor in his production process is substantially greater than the ratio of the rental rate on machinery to the wage rate for assembly-line labor. How should he alter his use of capital and labor to minimize the cost of production?To minimize cost, the manufacturer should use a combination of capital and labor so the rate atwhich he can trade capital for labor in his production process is the same as the rate at which hecan trade capital for labor in external markets. The manufacturer would be better off if heincreased his use of capital and decreased his use of labor, decreasing the marginal rate oftechnical substitution, MRTS. He should continue this substitution until his MRTS equals theratio of the rental rate to the wage rate.4. Why are isocost lines straight lines?The isocost line represents all possible combinations of labor and capital that may be purchasedfor a given total cost. The slope of the isocost line is the ratio of the input prices of labor andcapital. If input prices are fixed, then the ratio of these prices is clearly fixed and the isocost lineis straight. Only when the ratio or factor prices change as the quantities of inputs change is theisocost line not straight.5. If the marginal cost of production is increasing, does this tell you whether the average variable cost is increasing or decreasing? Explain.Marginal cost can be increasing while average variable cost is either increasing or decreasing. Ifmarginal cost is less (greater) than average variable cost, then each additional unit is adding less(more) to total cost than previous units added to the total cost, which implies that the AVCdeclines (increases). Therefore, we need to know whether marginal cost is greater than averagecost to determine whether the AVC is increasing or decreasing.6. If the marginal cost of production is greater than the average variable cost, does this tell you whether the average variable cost is increasing or decreasing? Explain.If the average variable cost is increasing (decreasing), then the last unit produced is adding more(less) to total variable cost than the previous units did, on average. Therefore, marginal cost isabove (below) average variable cost. If marginal cost is above average variable cost, averagevariable cost is also increasing.7. If the firm’s average cost curves are U-shaped, why does its average variable cost curve achieve its minimum at a lower level of output than the average total cost curve?Total cost is equal to fixed plus variable cost. Average total cost is equal to average fixed plusaverage variable cost. When graphed, the difference between the U-shaped total cost andaverage variable cost curves is the average fixed cost curve. If fixed cost is greater than zero, theminimum of average variable cost must be less than the minimum average total cost.8. If a firm enjoys increasing returns to scale up to a certain output level, and then constant returns to scale, what can you say about the shape of the firm’s long-run average cost curve?When the firm experiences increasing returns to scale, its long-run average cost curve isdownward sloping. When the firm experiences constant returns to scale, its long-run averagecost curve is horizontal. If the firm experiences increasing returns to scale, then constantreturns to scale, its long-run average cost curve falls, then becomes horizontal.9. How does a change in the price of one input change the firm’s long-run expansion path?The expansion path describes the combination of inputs for which the firm chooses to minimizecost for every output level. This combination depends on the ratio of input prices: if the price ofone input changes, the price ratio also changes. For example, if the price of an input increases,less of the input may be purchased for the same total cost. The intercept of the isocost line onthat input’s axis moves closer to the origin. Also, the slope of the isocost line, the price ratio,changes. As the price ratio changes, the firm substitutes away from the now more expensiveinput toward the cheaper input. Thus, the expansion path bends toward the axis of the nowcheaper input. See Exercise (7.6).10. Distinguish between economies of scale and economies of scope. Why can one be present without the other?Economies of scale refer to the production of one good and occur when proportionate increases inall inputs lead to a more-than-proportionate increase in output. Economies of scope refer to theproduction of more than one good and occur when joint output is less costly than the sum of thecosts of producing each good or service separately. There is no direct relationship betweenincreasing returns to scale and economies of scope, so production can exhibit one without theother. See Exercise (13) for a case with constant product-specific returns to scale andmultiproduct economies of scope.1. Assume a computer firm’s marginal costs of production are constant at $1,000 per computer. However, the fixed costs of production are equal to $10,000.a. Calculate the firm’s average variable cost and average total cost curves.The variable cost of producing an additional unit, marginal cost, is constant at $1,000, so theaverage variable cost is constant at $1,000, ()000,1$000,1$=QQ . Average fixed cost is $10,000Q. Average total cost is the sum of average variable cost and average fixed cost: ATC Q=+$1,$10,.000000 b. If the firm wanted to minimize the average total cost of production, would it choose to be verylarge or very small? Explain.The firm should choose a very large output because average total cost decreases with increase inQ . As Q becomes infinitely large, ATC will equal $1,000.2. If a firm hires a currently unemployed worker, the opportunity cost of utilizing t he worker’s service is zero. Is this true? Discuss.From the worker’s perspective, the opportunity cost of his or her time is the time not spent inother ways, including time spent in personal or leisure activities. Certainly, the opportunity costof hiring an unemployed mother of pre-school children is not zero! While it might be difficult toassign a monetary value to the time of an unemployed worker, we can not conclude that it is zero.From the perspective of the firm, the opportunity cost of hiring the worker is not zero, and thefirm could purchase a piece of machinery rather than hiring the worker.3.a. Suppose that a firm must pay an annual franchise fee, which is a fixed sum, independent of whether it produces any output. How does this tax aff ect the firm’s fixed, marginal, and average costs?Total cost, TC , is equal to fixed cost, FC , plus variable cost, VC . Fixed costs do not vary with thequantity of output. Because the franchise fee, FF , is a fixed sum, the firm’s fixed costs increaseby this fee. Thus, average cost, equal toFC VC Q +, and average fixed cost, equal to FC Q , increase by the average franchise fee FF Q. Note that the franchise fee does not affect average variable cost. Also, because marginal cost is the change in total cost with the production of anadditional unit and because the fee is constant, marginal cost is unchanged.3.b. Now suppose the firm is charged a tax that is proportional to the number of items it produces. Ag ain, how does this tax affect the firm’s fixed, marginal, and average costs?Let t equal the per unit tax. When a tax is imposed on each unit produced, variable costsincrease by tQ . Average variable costs increase by t , and because fixed costs are constant,average (total) costs also increase by t . Further, because total cost increases by t with eachadditional unit, marginal costs increase by t .4. A recent issue of Business Week reported the following:During the recent auto sales slump, GM, Ford, and Chrysler decidedit was cheaper to sell cars to rental companies at a loss than to lay offworkers. That’s because closing and reopening plants is expensive,partly because the auto makers’ current union contracts obligatethem to pay many wor kers even if they’re not working.When the article discusses selling cars “at a loss,” is it referring to accountingprofit or economic profit? How will the two differ in this case? Explainbriefly.When the article refers to the car companies selling at a loss, it is referring to accounting profit.The article is stating that the price obtained for the sale of the cars to the rental companies was less than their accounting cost. Economic profit would be measured by the difference of theprice with the opportunity cost of the cars. This opportunity cost represents the market valueof all the inputs used by the companies to produce the cars. The article mentions that the carcompanies must pay workers even if they are not working (and thus producing cars). Thisimplies that the wages paid to these workers are sunk and are thus not part of the opportunitycost of production. On the other hand, the wages would still be included in the accountingcosts. These accounting costs would then be higher than the opportunity costs and wouldmake the accounting profit lower than the economic profit.5. A chair manufacturer hires its assembly-line labor for $22 an hour and calculates that the rental cost of its machinery is $110 per hour. Suppose that a chair can be produced using 4 hours of labor or machinery in any combination. If the firm is currently using 3 hours of labor for each hour of machine time, is it minimizing its costs of production? If so, why? If not, how can it improve the situation?If the firm can produce one chair with either four hours of labor or four hours of capital,machinery, or any combination, then the isoquant is a straight line with a slope of -1 andintercept at K = 4 and L = 4, as depicted in Figure 7.5.The isocost line, TC = 22L + 110K has a slope of -=-2211002. when plotted with capital on the vertical axis and has intercepts at K TC =110 and L TC =22. The cost minimizing point is a corner solution, where L = 4 and K = 0. At that point, total cost is $88.6. Suppose the economy takes a downturn, and that labor costs fall by 50 percent and are expected to stay at that level for a long time. Show graphically how this change in the relative price of labor and capital affects the firm’s expansion path.Figure 7.6 shows a family of isoquants and two isocost curves. Units of capital are on the verticalaxis and units of labor are on the horizontal axis. (Note: In drawing this figure we have assumedthat the production function underlying the isoquants exhibits constant returns to scale, resultingin linear expansion paths. However, the results do not depend on this assumption.)If the price of labor decreases while the price of capital is constant, the isocost curve pivotsoutward around its intersection with the capital axis. Because the expansion path is the set ofpoints where the MRTS is equal to the ratio of prices, as the isocost curves pivot outward, theexpansion path pivots toward the labor axis. As the price of labor falls relative to capital, thefirm uses more labor as output increases.business when costs are cheaper and discourage off-peak business when costs are higher.Do you follow the consultant’s advice? Discuss.The consultant does not understand the definition of average cost. Encouraging ridership always decreases average costs, peak or off-peak. If ridership falls to 10, costs climb to $3.00 per rider. Further, during rush hour, the buses are full. How could more people get on? Instead, encourage passengers to switch from peak to off-peak times, for example, by charging higher prices during peak periods.MC 2 is the marginal cost of refining distillate up to the capacity constraint, Q 2. The shape of thetotal marginal cost curve is horizontal up to the lower capacity constraint. If the capacityconstraint of the distilling unit is lower than that of the hydrocracking unit, MC T is vertical at Q 1.If the capacity constraint of the hydrocracking unit is lower than that of the distilling unit, MC T isvertical at Q 2.9. You manage a plant that mass produces engines by teams of workers using assembly machines. The technology is summarized by the production function.Q 4 KLwhere Q is the number of engines per week, K is the number of assembly machines, and L is the number of labor teams. Each assembly machine rents for r = $12,000 per week and each team costs w = $3,000 per week. Engine costs are given by the cost of labor teams and machines, plus $2,000 per engine for raw materials. Your plant has a fixed installation of 10 assembly machines as part of its design.a. What is the cost function for your plant — namely, how much would it cost to produce Qengines? What are average and marginal costs for producing Q engines? How do average costs vary with output?K is fixed at 10. The short-run production function then becomes Q = 40 L. This implies that for any level of output Q, the number of labor teams hired will be L = Q / 40. The total cost function is thusgiven by the sum of the costs of capital, labor, and raw materials:TC(Q) = rK + wL + 2000Q = (12,000)(10) + (3,000)(Q/40) + 2,000 Q= 120,000 + 2,075QThe average cost function is then given by:AC(Q) = TC(Q)/Q = 120,000/Q + 2,075and the marginal cost function is given by:∂ TC(Q) / ∂ Q = 2,075Marginal costs are constant and average costs will decrease as quantity increases (due to the fixed cost of capital).b. How many teams are required to producing 80 engines? What is the average cost perengine?To produce Q = 80 engines we need L = Q/40 labor teams or L = 2. Average costs are given byAC(Q) = 120,000/Q + 2,075or AC = 3575 c. You are asked to make recommendations for the design of a new production facility. Whatwould you suggest? In particular, what capital/labor (K/L) ratio should the new plant accommodate? If lower average cost were your only criterion, should you suggest that the new plant have more production capacity or less production capacity that the plant you currently manage?We no longer assume that K is fixed at 10. We need to find the combination of K and L which minimizes costs at any level of output Q. The cost-minimization rule is given byMP r =MP w .KLTo find the marginal product of capital, observe that increasing K by 1 unit increases Q by 4L, so MP K = 4L. Similarly, observe that increasing L by 1 unit increases Q by 4K, so MP L = 4K. (Mathematically, MP K = ∆Q /∆K = 4L and MP L = ∆Q /∆L = 4K.) Using these formulas in the cost-minimization rule, we obtain:4L/r = 4K/w or K / L = w / r = 3,000 / 12,000 = 1/4The new plant should accommodate a capital to labor ratio of 1 to 4.The firm’s capital -labor ratio is currently 10/2 or 5. To reduce average cost, the firm should either use more labor and less capital to produce the same output or it should hire more labor and increase output.*10. A computer company’s cost function, which relates its average cost of product ion AC to its cumulative output in thousands of computers CQ and its plant size in terms of thousands of computers produced per year Q, within the production range of 10,000 to 50,000 computers is given byAC = 10 - 0.1CQ + 0.3Q.a. Is there a learning curve effect?The learning curve describes the relationship between the cumulative output and the inputsrequired to produce a unit of output. Average cost measures the input requirements per unit ofoutput. Learning curve effects exist if average cost falls with increases in cumulative output.Here, average cost decreases as cumulative output, CQ, increases. Therefore, there are learningcurve effects.b. Are there increasing or decreasing returns to scale?To measure scale economies, calculate the elasticity of total cost, TC, with respect to output, Q:ETCTCQQTCTCQMCACC ===∆∆∆∆.If this elasticity is greater (less) than one, then there are decreasing (increasing) returns to scale, because total costs are rising faster (slower) than output. From average cost we can calculate total and marginal cost:TC = Q(AC) = 10Q - (0.1)(CQ)(Q) + 0.3Q2, thereforeMCdTCdQCQ Q ==-+100106...Because marginal cost is greater than average cost (because 0.6Q > 0.3Q), the elasticity, EC, is greater than one; there are decreasing returns to scale. The production process exhibits a learningeffect and decreasing returns to scale.c. During its existence, the firm has produced a total of 40,000 computers and is producing 10,000computers this year. Next year it plans to increase its production to 12,000 computers. Will its average cost of production increase or decrease? Explain.First, calculate average cost this year:AC1= 10 - 0.1CQ + 0.3Q = 10 - (0.1)(40) + (0.3)(10) = 9.Second, calculate the average cost next year:AC2= 10 - (0.1)(50) + (0.3)(12) = 8.6.(Note: Cumulative output has increased from 40,000 to 50,000.) The average cost will decreasebecause of the learning effect.11. The short-run cost function of a company is given by the equation C = 190 + 53Q, where C is the total cost and Q is the total quantity of output, both measured in tens of thousands.a. What is the company’s fixed cost?When Q = 0, C = 190 (or $1,900,000). Therefore, fixed cost is equal to 190 (or $1,900,000).b. If the company produced 100,000 units of goods, what is its average variable cost?With 100,000 units, Q= 10. Variable cost is 53Q= (53)(10) = 530 (or $5,300,000). Averagevariable cost is TVCQ==$530$53.10c. What is its marginal cost per unit produced?With constant average variable cost, marginal cost is equal to average variable cost, $53.d. What is its average fixed cost?At Q = 10, average fixed cost is TFCQ==$190$1910.e. Suppose the company borrows money and expands its factory. Its fixed cost rises by $50,000,but its variable cost falls to $45,000 per 10,000 units. The cost of interest (I) also enters into the equation. Each one-point increase in the interest rate raises costs by $30,000. Write the new cost equation.Fixed cost changes from 190 to 195. Variable cost decreases from 53 to 45. Fixed cost alsoincludes interest charges: 3I . The cost equation isC = 195 + 45Q + 3I .*12. Suppose the long-run total cost function for an industry is given by the cubic equation TC = a + bQ + cQ 2 + dQ 3. Show (using calculus) that this total cost function is consistent with a U-shaped average cost curve for at least some values of a, b, c, d.To show that the cubic cost equation implies a U -shaped average cost curve, we use algebra,calculus, and economic reasoning to place sign restrictions on the parameters of the equation.These techniques are illustrated by the example below.First, if output is equal to zero, then TC = a , where a represents fixed costs. In the short run,fixed costs are positive, a > 0, but in the long run, where all inputs are variable a = 0. Therefore,we restrict a to be zero.Next, we know that average cost must be positive. Dividing TC by Q:AC = b + cQ + dQ 2.This equation is simply a quadratic function. When graphed, it has two basic shapes: a U shapeand a hill shape. We want the U shape, i.e., a curve with a minimum (minimum average cost),rather than a hill shape with a maximum.To the left of the minimum, the slope should be negative (downward sloping). At the minimum,the slope should be zero, and to the right of the minimum the slope should be positive (upwardsloping). The first derivative of the average cost curve with respect to Q must be equal to zero atthe minimum. For a U -shaped AC curve, the second derivative of the average cost curve must bepositive.The first derivative is c + 2dQ ; the second derivative is 2d . If the second derivative is to bepositive, then d > 0. If the first derivative is equal to zero, then solving for c as a function of Qand d yields: c = -2dQ . If d and Q are both positive, then c must be negative: c < 0.To restrict b , we know that at its minimum, average cost must be positive. The minimum occurswhen c + 2dQ = 0. We solve for Q as a function of c and d : Q c=->0. Next, substitutingthis value for Q into our expression for average cost, and simplifying the equation:2222⎪⎪⎭⎫ ⎝⎛-⎪⎪⎭⎫ ⎝⎛-++=++=d c d c d c b dQ cQ b AC , orAC b b b c d cd cd c d c d =-=-+=->+2222223362660. implying b c d >26. Because c 2and d > 0, b must be positive.In summary, for U -shaped long-run average cost curves, a must be zero, b and d must be positive, cmust be negative, and 4db > c 2. However, the conditions do not insure that marginal cost is positive.To insure that marginal cost has a U shape and that its minimum is positive, using the sameprocedure, i.e., solving for Q at minimum marginal cost -c d /,3 and substituting into theexpression for marginal cost b + 2cQ + 3dQ 2, we find that c 2 must be less than 3bd . Notice thatparameter values that satisfy this condition also satisfy 4db > c 2, but not the reverse.where a, b, and c are positive. Is this total cost function consistent with the presence of economies or diseconomies of scale? With economies or diseconomies of scope?There are two types of scale economies to consider: multiproduct economies of scale and product-specific returns to scale. From Section 7.5 we know that multiproduct economies of scalefor the two-product case, S H,S , are()()()()()S H S H MC S MC H S H TC S +=, , where MC H is the marginal cost of producing hardware and MC S is the marginal cost of producingsoftware. The product-specific returns to scale are:()()()()H H MC H S TC S H TC S ,0 , -= and ()()()()S S MC S H TC S H TC S 0, , -= where TC (0,S ) implies no hardware production and TC (H ,0) implies no software production. Weknow that the marginal cost of an input is the slope of the total cost with respect to that input.Since()(),S cH b aH bS H cS a TC -+=+-=we have MC H = a - cS and MC S = b - cH .Substituting these expressions into our formulas for S H,S , S H , and S S :()()cH b S cS a H cHS bS aH S S H -+--+=, or S aH bS cHS H S ,=+-+->1, because cHS > 0. Also, ()()cS a H bS cHS bS aH S H ---+=, or()()()()1=--=--=cS a cS a cS a H cHS aH S H and similarly ()().1=---+=cH b S aH cHS bS aH S S There are multiproduct economies of scale, S H,S > 1, but constant product-specific returns to scale,S H = S C = 1.Economies of scope exist if S C > 0, where (from equation (7.8) in the text):()()()()S H TC S H TC S TC H TC S c , , ,0 0, -+=, or, ()()S H TC cHS bS aH bS aH S c , -+-+=, or ().0, >=S H TC cHS S c Because cHS and TC are both positive, there are economies of scope.CHAPTER 8PROFIT MAXIMIZATION AND COMPETITIVE SUPPLYAs the title implies, this chapter covers two interrelated topics: a consideration of the behavioral incentives of the profit-maximizing firm and an examination of the interaction of these firms in a competitive market. The chapter begins with a discussion of whether firms maximize profits and ends with a discussion of the criteria for a competitive market, including an introduction to contestable markets. Exercises (1), (2), and (4) rely on data discussed in the text, while Exercises (3), (6), and (7) focus on the determination of the firm’s profit -maximizing quantity. Exercises (5), (8), and (9) consider the influence of taxes on firms’ output in a competitive market.S ections 8.2 through 8.4 derive the firm’s supply curve. Although total revenue is easily understood, you will need to show why average revenue may be represented by the demand curve. Demand and average revenue will be used interchangeably in Chapters 10 and 11. When presented with a problem involving the derivation of marginal revenue, some students will substitute Q , instead of P , in the expression for total revenue. This leads to revenue as a function of price. Stress that when they are given a demand curve in these applications they should first solve for price as a function of quantity. The origin of this confusion could lie in the popular notion that the firm determines the profit-maximizing price instead of the profit-maximizing quantity. Emphasize the importance of quantity, for example, when discussing why deviations from the profit-maximizing quantity lead to a decrease in profit (see Figure 8.3). Using the solutions to the exercises, emphasize that, for a linear demand curve, the slope of the marginal revenue curve is twice the slope of the demand curve.Other sources of confusion arise during analysis of firms’ supply curves. Stress that, as a primary rule, the firm should choose a quantity such that marginal revenue is equal to marginal cost. In this chapter, we can simplify this rule: for a firm facing a perfectly elastic demand curve, price is equal to marginal revenue. Stress that the rule for the competitive firm is a special case. Although some students will understand references to second-order conditions, expect to be asked why q 0 in Figure 8.3 is not profit maximizing, although MR = MC . Two additional points warrant careful explanation: 1) why the firm would remain in business if the firm sustains a loss in the short run, and 2) that maximizing profit is the same as minimizing loss.Although the summation of firm supply curves into a market supply curve is easy, the analysis of long-run competitive equilibrium is difficult. Show that long-run equilibrium relies on profit maximization by firms. Accompanying the rule that price must be greater than average variable cost in the short run, there is the assumption of free entry and exit. This leads to the statement that price must equal long-run average cost, LAC, as no firm may make an economic profit. The rule that price must equal long-run marginal cost, LMC , is the second equilibrium condition. Therefore, because LAC = LMC at minimum LAC , price is equal to minimum LAC in the long-run equilibrium. This result will be reconsidered in Chapter 12 in the discussion of equilibrium for a monopolistically competitive firm. When discussing the attainment of equilibrium in constant, increasing, and。
平狄克微观经济学笔记 (8)
CHAPTER 8PROFIT MAXIMIZATION AND COMPETITIVE SUPPLYTEACHING NOTESThis chapter identifies the behavioral incentives of the profit-maximizing firm and then explores the interaction of these firms in a competitive market. Each section of the chapter is important and builds a solid understanding of the supply side of the competitive market. It is necessary to build this foundation before moving on to the chapters in part III of the text. While the material in the chapter is written in a very clear, easy to understand manner, students still struggle with many of the concepts related to how the firm should choose the optimal quantity to produce, and how to apply the cost curve diagram learned in the previous chapter. One option for lecture is to spend time working with a table similar to the one used in the exercises at the end of the chapter. Working through many examples with this type of a table can help the students understand the different types of cost, as well as the firm’s optimal level of production.Section 8.1 identifies the three basic assumptions of perfect competition and section 8.2 discusses the assumption of profit maximization as the goal of the firm. Both sections are important in building the foundation for deriving the firm’s supply c urve, which is done in sections 8.3 to 8.5. Section 8.3 derives the general result that the firm should produce where marginal revenue is equal to marginal cost. The section then goes on to identify perfect competition as a special case where price is equal to marginal revenue, which follows directly from the assumption of price taker behavior in section 8.1. If your students have had calculus, it is helpful to derive the marginal revenue equals marginal cost rule by differentiating the profit function with respect to q. If your students have not had calculus then it is helpful to do some more work with the data tables so they understand that profit is maximized when marginal revenue equals marginal cost. Emphasize that the perfectly competitive firm chooses quantity and not price in order to maximize profit.To put perfect competition in perspective, it can also be helpful to give a brief overview of monopoly, oligopoly, and monopolistic competition before presenting the assumptions of perfect competition. Restrict this discussion to identifying how many firms are in the industry, if there are barriers to entry, product differentiation, and what assumptions does each firm make about how the other firms in the industry will react to their price and quantity decisions. This will stimulate the student’s interest about upcoming lectures.Sections 8.4 and 8.5 further explore the firm’s decision to produce where price is equal to marginal cost, and show that the firm’s supply curve is its marginal cost c urve above its average variable cost curve. Although some students will understand references to second-order conditions,in Figure 8.3 is not profit maximizing, although MR = MC. Two additional expect to be asked why qpoints warrant careful explanation: 1) why the firm would remain in business if the firm sustains a loss in the short run, and 2) that maximizing profit is the same as minimizing loss.Although the summation of firm supply curves into a market supply curve is straightforward, the analysis of long-run competitive equilibrium is difficult. Difficult concepts include:*why it may be optimal for the firm to incur losses in the short run but not the long run.*why free entry and exit will reduce economic profit to zero in the long run.*why price is equal to minimum average cost in the long run.It can be helpful to present an example, algebraic and graphical, which starts out with only one firm in the industry that is earning positive economic profit, and then show how the market will converge on its long run equilibrium point. Explore changes in price, quantity produced, and the level of profits, and relate the changes to the firm’s behavioral motivations.This chapter introduces two other important topics that will be elaborated on in Chapter 9: producer surplus and economic rent. Students frequently confuse profit, producer surplus, and economic rent.REVIEW QUESTIONS1. Why would a firm that incurs losses choose to produce rather than shut down?Losses occur when revenues do not cover total costs. Revenues could be greater thanvariable costs, but not total costs, in which case the firm is better off producing in theshort run rather than shutting down, even though they are incurring a loss. The firmshould compare the level of loss with no production to the level of loss with positiveproduction, and pick the option that results in the smallest loss. In the short run, losseswill be minimized as long as the firm covers its variable costs. In the long run, all costsare variable, and thus, all costs must be covered if the firm is to remain in business.2. Explain why the industry supply curve is not the long-run industry marginal cost curve.In the short run, a change in the market price induces the profit-maximizing firm tochange its optimal level of output. This optimal output occurs when price is equal tomarginal cost, as long as marginal cost exceeds average variable cost. Therefore, thesupply curve of the firm is its marginal cost curve, above average variable cost. (Whenthe price falls below average variable cost, the firm will shut down.)In the long run, the firm adjusts its inputs so that its long-run marginal cost is equal tothe market price. At this level of output, it is operating on a short-run marginal costcurve where short-run marginal cost is equal to price. As the long-run price changes,the firm gradually changes its mix of inputs to minimize cost. Thus, the long-runsupply response is this adjustment from one set of short-run marginal cost curves toanother.Note also that in the long run there will be entry and the firm will earn zero profit, sothat any level of output where MC>AC is not possible.3. In long-run equilibrium, all firms in the industry earn zero economic profit. Why is this true?The theory of perfect competition explicitly assumes that there are no entry or exitbarriers to new participants in an industry. With free entry, positive economic profitsinduce new entrants. As these firms enter, the supply curve shifts to the right, causinga fall in the equilibrium price of the product. Entry will stop, and equilibrium will beachieved, when economic profits have fallen to zero.4. What is the difference between economic profit and producer surplus?While economic profit is the difference between total revenue and total cost, producersurplus is the difference between total revenue and total variable cost. The differencebetween economic profit and producer surplus is the fixed cost of production.5. Why do firms enter an industry when they know that in the long run economic profit will be zero?Firms enter an industry when they expect to earn economic profit. These short-runprofits are enough to encourage entry. Zero economic profits in the long run implynormal returns to the factors of production, including the labor and capital of theowners of firms. For example, the owner of a small business might experience positiveaccounting profits before the foregone wages from running the business are subtractedfrom these profits. If the revenue minus other costs is just equal to what could beearned elsewhere, then the owner is indifferent to staying in business or exiting.6. At the beginning of the twentieth century, there were many small American automobile manufacturers. At the end of the century, there are only three large ones. Suppose that this situation is not the result of lax federal enforcement of antimonopoly laws. How do you explain the decrease in the number of manufacturers? (Hint: What is the inherent cost structure of the automobile industry?)Automobile plants are highly capital-intensive. Assuming there have been noimpediments to competition, increasing returns to scale can reduce the number of firmsin the long run. As firms grow, their costs decrease with increasing returns to scale.Larger firms are able to sell their product for a lower price and push out smaller firmsin the long run. Increasing returns may cease at some level of output, leaving morethan one firm in the industry.7. Industry X is characterized by perfect competition, so every firm in the industry is earning zero economic profit. If the product price falls, no firms can survive. Do you agree or disagree? Discuss.Disagree. As the market price falls, firms cut their production. If price falls belowaverage total cost, firms continue to produce in the short run and cease production inthe long run. If price falls below average variable costs, firms cease production in theshort run. Therefore, with a small decrease in price, i.e., less than the differencebetween the price and average variable cost, the firm can survive. With larger pricedecrease,i.e., greater than the difference between price and minimum average cost, thefirm cannot survive. In general, we would expect that some firms will survive and thatjust enough firms will leave to bring profit back up to zero.8. An increase in the demand for video films also increases the salaries of actors and actresses. Is the long-run supply curve for films likely to be horizontal or upward sloping? Explain.The long-run supply curve depends on the cost structure of the industry. If there is afixed supply of actors and actresses, as more films are produced, higher salaries must beoffered. Therefore, the industry experiences increasing costs. In an increasing-costindustry, the long-run supply curve is upward sloping. Thus, the supply curve forvideos would be upward sloping.9. True or false: A firm should always produce at an output at which long-run average cost is minimized. Explain.False. In the long run, under perfect competition, firms will produce where long-runaverage costs are minimized. In the long-run, the firm will have adjusted its mix ofcapital and labor so that average costs are minimized. In addition, entry and exit willforce price to adjust so it is close to minimum average cost. In the short run, however,the firm might not be producing the optimal long-run output. For example, if there areany fixed factors of production, the firm does not always produce where long-runaverage cost is minimized. Also, in the short run the firm may be producing at a pointwhere price equals marginal cost at a quantity that is different than that whichcorresponds to minimum long-run average cost.10. Can there be constant returns to scale in an industry with an upward-sloping supply curve? Explain.Constant returns to scale imply that proportional increases in all inputs yield the sameproportional increase in output. Proportional increases in inputs can induce higherprices if the supply curves for these inputs are upward sloping. For example, productionthat uses rare or depleting inputs will see higher costs of production as productionincreases in scale. Doubling inputs will still yield double output, but because of risingcosts, the firm cannot offer increasing amounts of the good without higher prices.Therefore, constant returns to scale does not always imply long-run horizontal supplycurves.11. What assumptions are necessary for a market to be perfectly competitive? In light of what you have learned in this chapter, why is each of these assumptions important?The two primary assumptions of perfect competition are (1) all firms in the industry areprice takers, and (2) there is free entry and exit of firms from the market. This chapterdiscusses how competitive equilibrium is achieved under these assumptions. The firstassumption is important because it means that no firm has any market power. Givenno firm has market power, firms will produce where price is equal to marginal cost. Inthe short run, price could equal marginal cost at a quantity where marginal cost isgreater than average cost, implying positive economic profits. With free entry and exit,positive economic profits would encourage other firms to enter. This entry exertsdownward pressure on price until price is equal to both marginal cost and minimumaverage cost.12. Suppose a competitive industry faces an increase in demand (i.e., the demand curve shifts upward). What are the steps by which a competitive market insures increased output? Will your answer change if the government imposes a price ceiling?If demand increases with fixed supply, price and profits increase. The price increaseinduces the firms in the industry to increase output. Also, with positive profit, firmsenter the industry, shifting the supply curve to the right. This results in a newequilibrium with a higher quantity produced and a price that earns all firms zeroeconomic profit. With an effective price ceiling, profit will be lower than without theceiling, reducing the incentive for firms to enter the industry. With zero economic profit,no firms enter and there is no shift in the supply curve.13. The government passes a law that allows a substantial subsidy for every acre of land used to grow tobacco. How does this program affect the long-run supply curve for tobacco?A subsidy on tobacco production decreases the firm’s costs of production. These costdecreases encourage other firms to enter tobacco production, and the supply curve forthe industry shifts out to the right14. A certain brand of vacuum cleaners can be purchased from several local stores as well as from several catalogue or web site sources.a.If all sellers charge the same price for the vacuum cleaner, will they all earn zeroeconomic profit in the long run?Yes by charging the same price they will all earn zero economic profit in the long run.If economic profit was greater than zero then firms would enter the industry and ifeconomic profit was less than zero firms would exit the industry.b.If all sellers charge the same price and one local seller owns the building in whichhe does business, paying no rent, is this seller earning a positive economic profit?No this seller would still earn zero economic profit. If he pays no rent then theaccounting cost of using the building is zero, but there is still an opportunity cost,which represents the value of the next best alternative use of the building.c.Does the seller who pays no rent have an incentive to lower the price he chargesfor the vacuum cleaner?No he has no incentive to charge a lower price because this will lower his economicprofit. Given all firms sell an identical good, they will charge the same price for thatgood. By charging a lower price, the firm is no longer maximizing profit.EXERCISES1. The data in the following table give information about the price (in dollars) for which a firm can sell a unit of output and the total cost of production.a.Fill in the blanks in the table.b.Show what happens to the firm’s output choice and profit if the price of the productfalls from $60 to $50.Q P TRP =60 TCπP = 60MC MRP = 60TRP = 50MRP =50πP = 500 60 1001 60 1502 60 1783 60 1984 60 2125 60 2306 60 2507 60 2728 60 3109 60 35510 60 41011 60 475The table below shows the firm’s revenue and cost for the two prices.Q P TRP =60 TCπP = 60MC MRP = 60TRP = 50MRP =50πP = 500 60 0 100 -100 ___ ___ 0 ___ -1001 60 60 150 -90 50 60 50 50 -1002 60 120 178 -58 28 60 100 50 -783 60 180 198 -18 20 60 150 50 -484 60 240 212 28 14 60 200 50 -125 60 300 230 70 18 60 250 50 206 60 360 250 110 20 60 300 50 507 60 420 272 148 22 60 350 50 788 60 480 310 170 38 60 400 50 909 60 540 355 185 45 60 450 50 9510 60 600 410 190 55 60 500 50 9011 60 660 475 185 65 60 550 50 75At a price of $60, the firm should produce ten units of output to maximize profit because this is the point closest to where price equals marginal cost without having marginalcost exceed price. At a price of $50, the firm should produce nine units to maximizeprofit. When price falls from $60 to $50, profit falls from $190 to $95.2. Using the data in the table, show what happens to the firm’s output choice and profit if the fixed cost of production increases from $100 to $150, and then to $200. Assume that the price of the output remains at $60 per unit. What general conclusion can you reach about the effects of fixed costs on the firm’s output choice?The table below shows the firm’s revenue and cost information for fixed cost, FC of 100,150, and 200.In all of the given cases, with fixed cost equal to 100, then 150, and then 200, the firmwill produce 10 units of output because this is the point closest to where price equalsmarginal cost without having marginal cost exceed price. Fixed costs do not influencethe optimal quantity, because they do not influence marginal cost. Higher fixed costsalso result in lower profits.Q P TR TCFC =100πFC =100MC TCFC = 150πFC = 150TCFC = 200πFC = 2000 60 0 100 -100 ___ 150 -150 200 -2001 60 60 150 -90 50 200 -140 250 -1902 60 120 178 -58 28 228 -108 278 -1583 60 180 198 -18 20 248 -68 298 -1184 60 240 212 28 14 262 -22 312 -725 60 300 230 70 18 280 20 330 -306 60 360 250 110 20 300 60 350 107 60 420 272 148 22 322 98 372 488 60 480 310 170 38 360 120 410 709 60 540 355 185 45 405 135 455 8510 60 600 410 190 55 460 140 510 9011 60 660 475 185 65 525 135 575 853. Use the same information as in Exercise 1.a. Derive the firm’s short-run supply curve. (Hint: you may want to plot theappropriate cost curves.)The firm’s short-run supply curve is its marginal cost curve above average variable cost.The table below lists marginal cost, total cost, variable cost, fixed cost, and averagevariable cost. The firm will produce 8 or more units depending on the market price andwill not produce in the 0-7 units of output range because in this range AVC is greaterthan MC. When AVC is greater than MC, the firm minimizes losses by producingnothing.Q TC MC TVC TFC AVC 0 100100 ___ 0 100 ___ 1 150 50 50 100 50.0 2 178 28 78 100 39.0 3 198 20 98 100 32.7 4 212 14 112 100 28.0 5 230 18 130 100 26.0 6 250 20 150 100 25.0 7 272 22 172 100 24.6 8 310 38 210 100 26.3 9 355 45 255 100 28.3 10 410 55 310 100 31.0 114756537510034.1b.If 100 identical firms are in the market, what is the industry supply curve? For 100 firms with identical cost structures, the market supply curve is the horizontal summation of each firm’s output at each price.80060QPS4. Suppose you are the manager of a watchmaking firm operating in a competitive market. Your cost of production is given by C = 200 +2 q2, where q is the level of output and C is total cost. (The marginal cost of production is 4q. The fixed cost of production is $200.)a. If the price of watches is $100, how many watches should you produce to maximizeprofit?Profits are maximized where marginal cost is equal to marginal revenue. Here,marginal revenue is equal to $100; recall that price equals marginal revenue in acompetitive market:100 = 4q, or q = 25.b. What will the profit level be?Profit is equal to total revenue minus total cost:π = (100)(25) - (200 + 2*252) = $1050.c. At what minimum price will the firm produce a positive output?A firm will produce in the short run if the revenues it receives are greater than itsvariable costs. Remember that the firm’s short-run supply curve is its marginal costcurve above the minimum of average variable cost. Here, average variable cost isVC q =2q2q=2q. Also, MC is equal to 4q. So, MC is greater than AVC for any quantitygreater than 0. This means that the firm produces in the short run as long as price ispositive.5. Suppose that a competitive firm’s marginal cost of producing output q is given by MC(q) = 3 + 2q. Assume that the mar ket price of the firm’s product is $9.a. What level of output will the firm produce?To maximize profits, the firm should set marginal revenue equal to marginal cost.Given the fact that this firm is operating in a competitive market, the market price itfaces is equal to marginal revenue. Thus, the firm should set the market price equal tomarginal cost to maximize its profits:9 = 3 + 2q, or q = 3.b. What is the firm’s producer surplus?Producer surplus is equal to the area below the market price, i.e., $9.00, and above themarginal cost curve, i.e., 3 + 2q. Because MC is linear, producer surplus is a trianglewith a base equal to $6 (9 - 3 = 6). The height of the triangle is 3, where P = MC.Therefore, producer surplus is(0.5)(6)(3) = $9.PriceQuantity123456789101234MC (q ) = 3 + 2qProducer’s SurplusP = $9.00Producer Surplusc.Suppose that the average variable cost of the firm is given by AVC(q) = 3 + q. Suppose that the firm’s fixed costs are known to be $3. Will the firm be earning a positive, negative, or zero profit in the short run?Profit is equal to total revenue minus total cost. Total cost is equal to total variable cost plus fixed cost. Total variable cost is equal to (AVC )(q ). Therefore, at q = 3,TVC = (3 + 3)(3) = $18.Fixed cost is equal to $3. Therefore, total cost equals TVC plus TFC , orTC = 18 + 3 = $21.Total revenue is price times quantity:TR = ($9)(3) = $27.Profit is total revenue minus total cost:π = $27 - $21 = $6.Therefore, the firm is earning positive economic profits. More easily, you might recall that profit equals producer surplus minus fixed cost. Since we found that producer surplus was $9 in part b, profit equals 9-3 or $6.6. A firm produces a product in a competitive industry and has a total cost functionT C =50+4q +2q 2and a marginal cost function MC =4+4q . At the given market price of $20, the firm is producing 5 units of output. Is the firm maximizing profit? What quantity of output should the firm produce in the long run?If the firm is maximizing profit, then price will be equal to marginal cost. P=MC results in P=20=4+4q=MC, or q=4. The firm is not maximizing profit, since it is producing too much output. The current level of profit isprofit = 20*5-(50+4*5+2*5*5) = –20,and the profit maximizing level isprofit = 20*4-(50+4*4+2*4*4) = –18.Given no change in the price of the product or the cost structure of the firm, the firm should produce q=0 units of output in the long run since at the quantity where price is equal to marginal cost, economic profit is negative. The firm should exit the industry.7. Suppose the cost function is C(q)=4q2+16.a.Find variable cost, fixed cost, average cost, average variable cost, and averagefixed cost. Hint: Marginal cost is MC=8q.Variable cost is that part of total cost that depends on q (4q2) and fixed cost is thatpart of total cost that does not depend on q (16).VC=4q2FC=16AC=C(q)q=4q+16qAVC=VCq=4qAFC=FCq=16qb.Show the average cost, marginal cost, and average variable cost curves on a graph.Average cost is u-shaped. Average cost is relatively large at first because the firm isnot able to spread the fixed cost over very many units of output. As output increases,average fixed costs will fall relatively rapidly. Average cost will increase at somepoint because the average fixed cost will become very small and average variable costis increasing as q increases. Average variable cost will increase because ofdiminishing returns to the variable factor labor. MC and AVC are linear, and bothpass through the origin. Average variable cost is everywhere below average cost.Marginal cost is everywhere above average variable cost. If the average is rising,then the marginal must be above the average. Marginal cost will hit average cost atits minimum point.c.Find the output that minimizes average cost.The minimum average cost quantity is where MC is equal to AC:AC=4q+16q=8q=MC16q=4q16=4q24=q22=q.d.At what range of prices will the firm produce a positive output?The firm will supply positive levels of output as long as P=MC>AVC, or as long as the firm is covering its variable costs of production. In this case, marginal cost is everywhere above average variable cost so the firm will supply positive output at any positive price.e.At what range of prices will the firm earn a negative profit?The firm will earn negative profit when P=MC<AC, or at any price below minimum average cost. In part c above we found that the minimum average cost quantity was q=2. Plug q=2 into the average cost function to find AC=16. The firm will therefore earn negative profit if price is below 16.f.At what range of prices will the firm earn a positive profit?In part e we found that the firm would earn negative profit at any price below 16.The firm therefore earns positive profit as long as price is above 16.8. A competitive firm has the following short run cost function:C(q)=q3-8q2+30q+5.a.Find MC, AC, and AVC and sketch them on a graph.The functions can be calculated as follows:MC=∂C∂q=3q2-16q+30AC=Cq=q2-8q+30+5qAVC=VCq=q2-8q+30Graphically, all three cost functions are u-shaped in that cost declines initially as q increases, and then cost increases as q increases. Average variable cost is below average cost. Marginal cost will be initially below AVC and will then increase to hit AVC at its minimum point. MC will be initially below AC and will also hit AC at its minimum point.b.At what range of prices will the firm supply zero output?The firm will find it profitable to produce in the short run as long as price is greater than or equal to average variable cost. If price is less than average variable cost then the firm will be better off shutting down in the short run, as it will only lose its fixed cost and not fixed plus some of variable cost. Here we need to find the minimum average variable cost, which can be done in two different ways. You can either set marginal cost equal to average variable cost, or you can differentiate average variable cost with respect to q and set this equal to zero. In both cases, you can solve for q and then plug into AVC to find the minimum AVC. Here we will set AVC equal to MC:AVC=q2-8q+30=3q2-16q+30=MC2q2=8qq=4AVC(q=4)=42-8*4+30=14.Hence, the firm supplies zero output if P<14.c.Identify the firm’s supply curve on your graph.The firm supply curve is the MC curve above the point where MC=AVC. The firm will produce at the point where price equals MC as long as MC is greater than or equal to AVC.d.At what price would the firm supply exactly 6 units of output?The firm maximizes profit by choosing the level of output such that P=MC. To find the price where the firm would supply 6 units of output, set q equal to 6 and solve for MC:P=MC=3q2-16q+30=3(62)-16(6)+30=42.9. a. Suppose that a firm’s production function is q=9x 12in the short run, where thereare fixed costs of $1,000 and x is the variable input, whose cost is $4,000 per unit. What is。
微观经济学第8章PPT课件
02
03
技术进步与创新
社会福利
市场竞争压力促使厂商不断进行 技术进步和创新，提高生产效率。
市场竞争能够降低价格、增加消 费者福利，但也可能导致过度竞 争和厂商利润下降。
市场失灵与政府干预
要点一
外部性
企业或个人的经济活动对第三方产生的影响未能通过市场 交易反映出来。
要点二
公共品
具有非排他性和非竞争性的产品，市场机制无法提供。
寡头市场
少数几家大厂商占据大部分市场份额，产品同质或差异较大 ，进出较难。
完全垄断市场
只有一家厂商，产品无替代品，价格和产量由厂商自行决定 。
市场类型与厂商行为
价格接受者
在完全竞争市场中，每个厂商都是价格接受者，没有 能力影响市场价格。
价格制定者
在垄断和寡头市场中，厂商有能力制定价格和产量。
成本最小化者
环境政策
限制污染排放和推动可持续发展。
信息披露政策
强制企业披露相关信息，减少信息不对称问题。
07
应用案例分析
价格控制与短缺经济
总结词
价格控制与短缺经济的关系
详细描述
当政府对某些商品或服务进行价格控制时，市场供需关系 失衡，导致短缺经济的出现。例如，政府对房租进行限制 ，租房市场可能出现供不应求的情况，导致一部分人无法 租到合适的住房。
微观经济学第8章ppt课件
• 引言 • 市场供需理论 • 弹性理论 • 消费者行为理论 • 生产者行为理论 • 市场结构与竞争策略 • 应用案例分析
01
引言
章节概述
01
本章主要介绍微观经济学中的市场失灵与政府干预。
02
通过分析市场失灵的原因和表现，探讨政府干预的必要性和 措施。
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完全竞争市场
产品同质
•所有厂商的产品互相之间是完全替代的——也就是说他们 是完全同质的，任何一个厂商如果想将其产品的价格提高到 市场价格之上必然失去顾客。 •相反，如果产品是异质的，则每一家厂商都有机会提高其 价格，而不会导致顾客流失。 •产品同质性的假定非常重要，因为它保证了单一市场价格 的存在，这使市场供求的分析变得有意义。
8.2 Profit maximization
8.3 Marginal Revenue, Marginal Cost, and Profit Maximization
8.4 Choosing Output in the Short Run
8.5 The Competitive Firm’s ShortRun Supply Curve
CHAPTER 8
利润最大化与竞争性供给
•完全竞争市场 •利润最大化 •边际收益、边际成本与利润最大化 •选择短期产量 •竞争性厂商的短期供给曲线 •短期市场供给曲线 •长期的产量选择 •行业的长期供给曲线
CHAPTER OUTLINE
8.1 Perfectly Competitive Markets
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边际收益、边际成本和利润最大化
•在竞争性市场上，单个厂商面对的需求曲线d既是它的平 均收益曲线，又是它的边际收益曲线。
•在这条曲线上，边际收益与价格相等。
MR=AR=P
竞争性厂商的利润最大化 完全竞争性厂商应该选择的产量是使边际成本等于价格：
MC(q) = MR = P
Copyright © 2013 Pearson Education, Inc. • Microeconomics • Pindyck/Rubinfeld, 8e.
•即使市场的需求弹性不是很大，这三个厂商也可能会激烈竞争
Copyright © 2013 Pearson Education, Inc. • Microeconomics • Pindyck/Rubinfeld, 8e.
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8.2
利润最大化
厂商最大化利润吗？
•微观经济学经常用到利润最大化的假设，因为它合理而准确地预测商业行 为并可避免不必要的分析上的混乱。
•在短期，如果价格高于1 140美 元/吨而低于1 300美元/吨，则工 厂就应该每天生产600吨铝。 •如果价格高于1 300美元/吨，则 厂商就应该要求加班，每天生产 900吨铝。而如果价格低于1 140 美元/吨，它就应该停止生产。 •但是如果它预期价格未来会上 升，它也可能继续生产。
图8.5 精炼铝工厂的短期产量
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8.2
其他组织形式
利润最大化
•合作社 •一些厂商或个人共同拥有的组织，由设施为共有，并要共同付钱来维护和管理 那些公共设施。
8.6 The Short-Run Market Supply Curve
8.7 Choosing Output in the Long-Run
8.8 The Industry’s Long-Run Supply Curve
Copyright © 2013 Pearson Education, Inc. • Microeconomics • Pindyck/Rubinfeld, 8e.
导原则： •第一，除了条件有限，平均可变成本不应用来替代 边际成本。
当前产量： 材料成本：
每天100单位，其中80单位属于正常生产，20单位属于加 班生产。 每单位产量8美元
人工成本：
正常工作时间30美元/单位；加班时间50美元/单位。
Copyright © 2013 Pearson Education, Inc. • Microeconomics • Pindyck/Rubinfeld, 8e.
Copyright © 2013 Pearson Education, Inc. • Microeconomics • Pindyck/Rubinfeld, 8e.
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完全竞争市场
自由的进入与退出
•不存在任何特别的成本使厂商难以进入（退出）某个行业 的情形
•购买者可以很容易地从一家厂商转向另一家厂商，厂 商也可以很容易地进入或者退出市场。
•有许多厂商的行业，由于厂商可以在价格制定上进行或明或暗的合谋， 对于判断是否大体上是完全竞争的，存在许多厂商这个条件并不充分。 •相反，市场上仅有几家厂商也不能排除竞争行为。
•假设市场上仅有三个厂商，但是产品的市场需求是非常富有弹性 的，那么每个厂商面临的需求曲线可能接近水平，厂商的行为就像 在完全竞争市场上一样。
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EXAMPLE 8.3 经理的一些成本考虑
•对边际收益等于边际成本这一准则的运用，取决于经理对边
际成本的估算能力。
•为获得有用的成本估算，经理应在心里牢记以下三条指
Prepared by: Fernando Quijano, Illustrator
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8.1
完全竞争市场
价格接受
每个厂商出售的产量占全部行业产量的比重足够小，以至于其决策对市 场价格不产生影响，所以每个厂商视价格为给定的。
价格接受者
● 对市场价格没有影响，因而只能接受给定价格的厂商。
Copyright © 2013 Pearson Education, Inc. • Microeconomics • Pindyck/Rubinfeld, 8e.
Copyright © 2013 Pearson Education, Inc. • Microeconomics • Pindyck/Rubinfeld, 8e.
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完全竞争市场
市场何时是高度竞争的
•除了农业，世界上几乎没有哪个市场是完全竞争的。然而，由于一些市场 是高度竞争的，厂商面对的是高弹性需求曲线，进入与退出都相对容易。 •没有一个简便的用于描述市场是否接近完全竞争的经验准则
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8.4
选择短期产量
竞争性厂商的短期利润最大化
•在短期，竞争性厂商 通过选择边际成本MC 与产品价格P(或边际 收益MR)相等的产量 来实现利润最大。
•厂商的利润由矩形 ABCD表示。
•任何较低的产量q1或 较高产量q2都将导致 利润下降。
利润为正
产出法则 如果一家厂商可以在任何产出水平生产，那么它 应当在边际收益等于边际成本的产出水平上生产。
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8.3 边际收益、边际成本和利润最大化
●利润 总收益与总成本的差额
π(q) = R(q) − C(q)
●边际收益 产量增加一个单位时总收益的变化量
•厂商选择产量q*，以使利润， 即收益R和成本C之差AB最大。 •在该产出水平上，边际收益( 收益曲线的斜率)等于边际成本 (成本曲线的斜率)。
•平均可变成本为劳动成本加材料成本，即42美元/单位。 •加班时间生产的产品单位边际成本为58美元/单位 •因为边际成本高于平均可变成本，依靠平均可变成本决策的经理可 能会生产过多的产品。
Copyright © 2013 Pearson Education, Inc. • Microeconomics • Pindyck/Rubinfeld, 8e.
•但厂商是否真的以利润最大化为目标，一直存在争议。 •对由所有者自己管理的小企业，利润似乎决定着差不多全部的企业决策。 •在大企业里，作日常决策的经理通常很少与所有者接触，结果导致企业的 所有者不能常规化地监督经理的行为。
•经理可能会更关心其他目标 •但是，企业要在竞争性行业中生存下去，就得将长期利润最大化作为 它们最优先考虑的目标之一。
•一座典型的共管公寓比相同条件下的合作公寓贵15.5%。 •显然，合作公寓形式并不是公寓价值最大化的一种最 佳方式。
•另一方面，合作公寓的拥有者在原先的邻居房屋出售时更 有对未来邻居的选择权——这些是纽约人更在乎的事项。
•因此，在纽约，许多人愿意放弃一些金钱而实现一些 非货币收益。
Copyright © 2013 Pearson Education, Inc. • Microeconomics • Pindyck/Rubinfeld, 8e.
Copyright © 2013 Pearson Education, Inc. • Microeconomics • Pindyck/Rubinfeld, 8e.
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EXAMPLE 8.1 纽约市的共管公寓与合作制公寓
•虽然共管住房的业主必须加入业主委员会来管理公共空间( 如门廊)，但他们仍能就如何管理各自的地方以尽可能实现 价值最大化做出决策。相反，合作制公寓的成员共同负担有 关公寓的所有未付抵押贷款，并且要服从更复杂的管理规章 制度。 •从全国来看，共管住房的形式比合作住房的形式更普遍， 几乎是10∶1。在这点上，纽约市与全国其他城市相比非常 不同——其合作住房更普遍，它与共管住房相比是4∶1。
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EXAMPLE 8.3 经理的一些成本考虑
当前产量：
材料成本： 人工成本：
每天100单位，其中80单位属于正常生产，20单位属于加 班生产。 每单位产量8美元
正常工作时间30美元/单位；加班时间50美元/单位。