微观经济学作业第7章作业(修订版)

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曼昆微观经济学课后练习英文答案(第七章)

✍ how to define and measure consumer surplus.✍ the link between sellers’ costs of producing a good and the supply curve.✍ how to define and measure producer surplus.✍ that the equilibrium of supply and demand maximizes total surplus in a market. CONTEXT AND PURPOSE:Chapter 7 is the first chapter in a three-chapter sequence on welfare economics and market efficiency. Chapter 7 employs the supply and demand model to develop consumer surplus and producer surplus as a measure of welfare and market efficiency. These concepts are then utilized in Chapters 8 and 9 to determine the winners and losers from taxation and restrictions on international trade.The purpose of Chapter 7 is to develop welfare economics—the study of how the allocation of resources affects economic well-being. Chapters 4 through 6 employed supply and demand in a positive framework, which focused on the question, “What is the equilibrium price and quantity in a market?” This chapter now addresses the normative question, “Is the equilibrium price and quantity in a market the best possible solution to the resource allocation problem, or is it simply the price and quantity that balance supply and demand?” Students will discover that under most circumstances the equilibrium price and quantity is also the one that maximizes welfare.KEY POINTS:? Consumer surplus equals buyers’ willingness to pay for a good minus the amount they actually pay for it, and it measures the benefit buyers get from participating in a market.Consumer surplus can be computed by finding the area below the demand curve and above the price.? Producer surplus equals the amount sellers receive for their goods minus their costs of production, and it measures the benefit sellers get from participating in a market. Producer surplus can be computed by finding the area below the price and above the supply curve.? An allocation of resources that maximizes the sum of consumer and producer surplus is said to be efficient. Policymakers are often concerned with the efficiency, as well as the equality, of economic outcomes.? The equilibrium of supply and demand maximizes the sum of consumer and producer surplus.That is, the invisible hand of the marketplace leads buyers and sellers to allocate resources efficiently.? Markets do not allocate resources efficiently in the presence of market failures such as market power or externalities.CHAPTER OUTLINE:I. Definition of welfare economics: the study of how the allocation of resources affects economic well-being.A. Willingness to Pay1. Definition of willingness to pay: the maximum amount that a buyer will pay for a good.2. Example: You are auctioning a mint-condition recording of Elvis Presley’s first album. Four buyers show up. Their willingness to pay is as follows:for John. Because John is willing to pay more than he has to for the album,he derives some benefit from participating in the market.3. Definition of consumer surplus: the amount a buyer is willing to pay for a good minus the amount the buyer actually pays for it.4. Note that if you had more than one copy of the album, the price in the auction would end up being lower (a little over $70 in the case of two albums) and both John and Paul would gain consumer surplus.B. Using the Demand Curve to Measure Consumer Surplus1. We can use the information on willingness to pay to derive a demand curve for the rare2. . Because the demand curve shows the buyers’ willingness to pay, we can use the demand curve to measure consumer surplus.C. How a Lower Price Raises Consumer Surplusare paying less for the product than before (area A on the graph).b. Because the price is now lower, some new buyers will enter the market and receive consumer surplus on these additional units of output purchased (area B on the graph).D. What Does Consumer Surplus Measure?1. Remember that consumer surplus is the difference between the amount that buyers are willing to pay for a good and the price that they actually pay.2. Thus, it measures the benefit that consumers receive from the good as the buyers themselves perceive it.III. Producer SurplusA. Cost and the Willingness to Sell1. Definition of cost: the value of everything a seller must give up to produce a good .2. Example: You want to hire someone to paint your house. You accept bids for the work from four sellers. Each painter is willing to work if the price you will pay exceeds her opportunity cost. (Note that this opportunity cost thus represents willingness to sell.) The costs are: ALTERNATIVE CLASSROOM EXAMPLE:Review the material on price ceilings from Chapter 6. Redraw the market for two-bedroom apartments in your town. Draw in a price ceiling below the equilibriumprice.Then go through:✍ consumer surplus before the price ceiling is put into place.✍ consumer surplus after the price ceiling is put into place.You will need to take some time to explain the relationship between the producers’ willingness to sell and the cost of producing the good. The relationship between cost and the supply curve is not as apparent as the relationship between the demand curve and willingness to pay. It is important to stress that consumer surplus is measured in monetary terms. Consumer surplus gives us a way to place a monetary cost on inefficient market outcomes (due to government involvement or market failure).except for Grandma. Because Grandma receives more than she would require to paint the house, she derives some benefit from producing in the market.4.Definition of producer surplus: the amount a seller is paid for a good minus the seller’s cost of providing it.5. Note that if you had more than one house to paint, the price in the auction would end up being higher (a little under $800 in the case of two houses) and both Grandma and Georgia would gain producer surplus.B. Using the Supply Curve to Measure Producer Surplus1. We can use the information on cost (willingness to sell) to derive a supply curve for2. marginal seller . Because the supply curve shows the sellers’ cost (willingness to sell), we can use the supply curve to measure producer surplus.are receiving more for the product than before (area C on the graph).b. Because the price is now higher, some new sellers will enter the market and receive producer surplus on these additional units of output sold (area D on the graph).D. Producer surplus is used to measure the economic well-being of producers, much like consumer surplus is used to measure the economic well-being of consumers.ALTERNATIVE CLASSROOM EXAMPLE:Review the material on price floors from Chapter 6. Redraw the market for anagricultural product such as corn. Draw in a price support above the equilibriumprice.Then go through:✍ producer surplus before the price support is put in place.✍ producer surplus after the price support is put in place.Make sure that you discuss the cost of the price support to taxpayers.IV.Market EfficiencyA. The Benevolent Social Planner1. The economic well-being of everyone in society can be measured by total surplus, which is the sum of consumer surplus and producer surplus:Total Surplus = Consumer Surplus + Producer SurplusTotal Surplus = (Value to Buyers – Amount Paid by Buyers) +(Amount Received by Sellers – Cost to Sellers)Because the Amount Paid by Buyers = Amount Received bySellers:2. Definition of efficiency: the property of a resource allocation of maximizing the total surplus received by all members of society .3. Definition of equality: the property of distributing economic prosperity uniformly the members of society .a. Buyers who value the product more than the equilibrium price will purchase the product; those who do not, will not purchase the product. In other words, the free market allocates the supply of a good to the buyers who value it most highly, as measured by their willingness to pay.b. Sellers whose costs are lower than the equilibrium price will produce the product; those whose costs are higher, will not produce the product. In other words, the free market allocates the demand for goods to the sellers who can produce it at the lowest cost.to the marginal buyer is greater than the cost to the marginal seller so total surplus would rise if output increases.b. At any quantity of output greater than the equilibrium quantity, the value of the product to the marginal buyer is less than the cost to the marginal seller so total surplus would rise if output decreases.3. Note that this is one of the reasons that economists believe Principle #6: Markets are usually a good way to organize economic activity.It would be a good idea to remind students that there are circumstances whenthe market process does not lead to the most efficient outcome. Examplesinclude situations such as when a firm (or buyer) has market power over priceor when there are externalities present. These situations will be discussed inlater chapters.Pretty Woman, Chapter 6. Vivien (Julia Roberts) and Edward (Richard Gere)negotiate a price. Afterward, Vivien reveals she would have accepted a lowerprice, while Edward admits he would have paid more. If you have done a goodjob of introducing consumer and producer surplus, you will see the light bulbsgo off above your students’ heads as they watch this clip.C. In the News: Ticket Scalping1. Ticket scalping is an example of how markets work to achieve an efficient outcome.2. This article from The Boston Globe describes economist Chip Case’s experience with ticket scalping.D. Case Study: Should There Be a Market in Organs?1. As a matter of public policy, people are not allowed to sell their organs.a. In essence, this means that there is a price ceiling on organs of $0.b. This has led to a shortage of organs.2. The creation of a market for organs would lead to a more efficient allocation of resources, but critics worry about the equity of a market system for organs.V. Market Efficiency and Market FailureA. To conclude that markets are efficient, we made several assumptions about how markets worked.1. Perfectly competitive markets.2. No externalities.B. When these assumptions do not hold, the market equilibrium may not be efficient.C. When markets fail, public policy can potentially remedy the situation. SOLUTIONS TO TEXT PROBLEMS:Quick Quizzes1. Figure 1 shows the demand curve for turkey. The price of turkey is P1 and the consumer surplus that results from that price is denoted CS. Consumer surplus is the amount a buyer is willing to pay for a good minus the amount the buyer actually pays for it. It measures the benefit to buyers of participating in a market.Figure 1 Figure 22. Figure 2 shows the supply curve for turkey. The price of turkey is P1 and the producer surplus that results from that price is denoted PS. Producer surplus is the amount sellers are paid for a good minus the sellers’ cost of providing it (measured by the supply curve). It measures the benefit to sellers of participating in a market.Figure 33. Figure 3 shows the supply and demand for turkey. The price of turkey is P1, consumer surplus is CS, and producer surplus is PS. Producing more turkeys than the equilibrium quantity would lower total surplus because the value to the marginal buyer would be lower than the cost to the marginal seller on those additional units.Questions for Review1. The price a buyer is willing to pay, consumer surplus, and the demand curve are all closely related. The height of the demand curve represents the willingness to pay of the buyers. Consumer surplus is the area below the demand curve and above the price, which equals the price that each buyer is willing to pay minus the price actually paid.2. Sellers' costs, producer surplus, and the supply curve are all closely related. The height of the supply curve represents the costs of the sellers. Producer surplus is the area below the price and above the supply curve, which equals the price received minus each seller's costs of producing the good.Figure 43. Figure 4 shows producer and consumer surplus in a supply-and-demand diagram.4. An allocation of resources is efficient if it maximizes total surplus, the sum of consumer surplus and producer surplus. But efficiency may not be the only goal of economic policymakers; they may also be concerned about equity the fairness of the distribution of well-being.5. The invisible hand of the marketplace guides the self-interest of buyers and sellers into promoting general economic well-being. Despite decentralized decision making and self-interested decision makers, free markets often lead to an efficient outcome.6. Two types of market failure are market power and externalities. Market power may cause market outcomes to be inefficient because firms may cause price and quantity to differ from the levels they would be under perfect competition, which keeps total surplus from being maximized. Externalities are side effects that are not taken into account by buyers and sellers. As a result, the free market does not maximize total surplus.Problems and Applications1. a. Consumer surplus is equal to willingness to pay minus the price paid. Therefore, Melissa’s willingness to pay must be $200 ($120 + $80).b. Her consumer surplus at a price of $90 would be $200 ? $90 = $110.c. If the price of an iPod was $250, Melissa would not have purchased one because the price is greater than her willingness to pay. Therefore, she would receive no consumer surplus.2. If an early freeze in California sours the lemon crop, the supply curve for lemons shifts to the left, as shown in Figure 5. The result is a rise in the price of lemons and a decline in consumer surplus from A + B + C to just A. So consumer surplus declines by the amount B + C.Figure 5 Figure 6In the market for lemonade, the higher cost of lemons reduces the supply of lemonade, as shown in Figure 6. The result is a rise in the price of lemonade and a decline in consumer surplus from D + E + F to just D, a loss of E + F. Note that an event that affects consumer surplus in one market often has effects on consumer surplus in other markets.3. A rise in the demand for French bread leads to an increase in producer surplus in the market for French bread, as shown in Figure 7. The shift of the demand curve leads to an increased price, which increases producer surplus from area A to area A + B + C.Figure 7The increased quantity of French bread being sold increases the demand for flour, as shown in Figure 8. As a result, the price of flour rises, increasing producer surplus from area Dto D + E + F. Note that an event that affects producer surplus in one market leads to effects on producer surplus in related markets.Figure 84. a.Figure 9b. When the price of a bottle of water is $4, Bert buys two bottles of water. His consumer surplus is shown as area A in the figure. He values his first bottle of water at $7, but pays only $4 for it, so has consumer surplus of $3. He values his second bottle of water at $5, but pays only $4for it, so has consumer surplus of $1. Thus Bert’s total consumer surplus is $3 + $1 = $4, which is the area of A in the figure.c. When the price of a bottle of water falls from $4 to $2, Bert buys three bottles of water, an increase of one. His consumer surplus consists of both areas A and B in the figure, an increase in the amount of area B. He gets consumer surplus of $5 from the first bottle ($7 value minus $2 price), $3 from the second bottle ($5 value minus $2 price), and $1 from the third bottle ($3 value minus $2 price), for a total consumer surplus of $9. Thus consumer surplus rises by $5 (which is the size of area B) when the price of a bottle of water falls from $4 to $2.5. a.Figure 10b. When the price of a bottle of water is $4, Ernie sells two bottles of water. His producer surplus is shown as area A in the figure. He receives $4 for his first bottle of water, but it costs only $1 to produce, so Ernie has producer surplus of $3. He also receives $4 for his second bottle of water, which costs $3 to produce, so he has producer surplus of $1. Thus Ernie’s total producer surplus is $3 + $1 = $4, which is the area of A in the figure.c. When the price of a bottle of water rises from $4 to $6, Ernie sells three bottles of water, an increase of one. His producer surplus consists of both areas A and B in the figure, an increase by the amount of area B. He gets producer surplus of $5 from the first bottle ($6 price minus $1 cost), $3 from the second bottle ($6 price minus $3 cost), and $1 from the third bottle ($6 price minus $5 price), for a total producer surplus of $9. Thus producer surplus rises by $5 (which is the size of area B) when the price of a bottle of water rises from $4 to $6.6. a. From Ernie’s supply schedule and Bert’s demand schedule, the quantityequilibrium quantity of two.b. At a price of $4, consumer surplus is $4 and producer surplus is $4, as shown in Problems 3 and 4 above. Total surplus is $4 + $4 = $8.c. If Ernie produced one less bottle, his producer surplus would decline to $3, as shown in Problem 4 above. If Bert consumed one less bottle, his consumer surplus would decline to $3, as shown in Problem 3 above. So total surplus would decline to $3 + $3 = $6.d. If Ernie produced one additional bottle of water, his cost would be $5, but the price is only $4, so his producer surplus would decline by $1. If Bert consumed one additional bottle of water, his value would be $3, but the price is $4, so his consumer surplus would decline by $1. So total surplus declines by $1 + $1 = $2.7. a. The effect of falling production costs in the market for stereos results in a shift to the right in the supply curve, as shown in Figure 11. As a result, the equilibrium price of stereos declines and the equilibrium quantity increases.Figure 11b. The decline in the price of stereos increases consumer surplus from area A to A + B + C + D, an increase in the amount B + C + D. Prior to the shift in supply, producer surplus was areas B + E (the area above the supply curve and below the price). After the shift in supply, producer surplus is areas E + F + G. So producer surplus changes by the amount F + G – B, which may be positive or negative. The increase in quantity increases producer surplus, while the decline in the price reduces producer surplus. Because consumer surplus rises by B + C + D and producer surplus rises by F + G – B, total surplus rises by C + D + F + G.c. If the supply of stereos is very elastic, then the shift of the supply curve benefits consumers most. To take the most dramatic case, suppose the supply curve were horizontal, as shown in Figure 12. Then there is no producer surplus at all. Consumers capture all the benefits of falling production costs, with consumer surplus rising from area A to area A + B.Figure 128. Figure 13 shows supply and demand curves for haircuts. Supply equals demand at a quantity of three haircuts and a price between $4 and $5. Firms A, C, and D should cut the hair of Ellen, Jerry, and Phil. Oprah’s willingness to pay is too low and firm B’s costs are too high, so they do not participate. The maximum total surplus is the area between the demand and supply curves, which totals $11 ($8 value minus $2 cost for the first haircut, plus $7 value minus $3 cost for the second, plus $5 value minus $4 cost for the third).Figure 139. a. The effect of falling production costs in the market for computers results in a shift to the right in the supply curve, as shown in Figure 14. As a result, the equilibrium price of computers declines and the equilibrium quantity increases. The decline in the price of computers increases consumer surplus from area A to A + B + C + D, an increase in the amount B + C + D.Figure 14 Figure 15Prior to the shift in supply, producer surplus was areas B + E (the area above thesupply curve and below the price). After the shift in supply, producer surplus isareas E + F + G. So producer surplus changes by the amount F + G – B, whichmay be positive or negative. The increase in quantity increases producer surplus,while the decline in the price reduces producer surplus. Because consumer surplusrises by B + C + D and producer surplus rises by F + G – B, total surplus rises byC +D + F + G.b. Because typewriters are substitutes for computers, the decline in the price of computers means that people substitute computers for typewriters, shifting the demand for typewriters to the left, as shown in Figure 15. The result is a decline in both the equilibrium price and equilibrium quantity of typewriters. Consumer surplus in the typewriter market changes from area A + B to A + C, a net change of C – B. Producer surplus changes from area C + D + E to area E, a net loss of C + D. Typewriter producers are sad about technological advances in computers because their producer surplus declines.c. Because software and computers are complements, the decline in the price and increase in the quantity of computers means that the demand for software increases, shifting the demand for software to the right, as shown in Figure 16. The result is an increase in both the price and quantity of software. Consumer surplus in the software market changes from B + C to A + B, anet change of A – C. Producer surplus changes from E to C + D + E, an increase of C + D, so software producers should be happy about the technological progress in computers.Figure 16d. Yes, this analysis helps explain why Bill Gates is one the world’s richest people, because his company produces a lot of software that is a complement with computers and there has been tremendous technological advance in computers.10. a. With Provider A, the cost of an extra minute is $0. With Provider B, the cost of anextra minute is $1.b. With Provider A, my friend will purchase 150 minutes [= 150 – (50)(0)]. WithProvider B, my friend would purchase 100 minutes [= 150 – (50)(1)].c. With Provider A, he would pay $120. The cost would be $100 with Provider B.Figure 17d. Figure 17 shows the friend’s demand. With Provider A, he buys 150 minutes andhis consumer surplus is equal to (1/2)(3)(150) – 120 = 105. With Provider B, hisconsumer surplus is equal to (1/2)(2)(100) = 100.e. I would recommend Provider A because he receives greater consumer surplus.11. a. Figure 18 illustrates the demand for medical care. If each procedure has a price of $100, quantity demanded will be Q1 procedures.Figure 18b. If consumers pay only $20 per procedure, the quantity demanded will be Q2 procedures. Because the cost to society is $100, the number of procedures performed is too large to maximize total surplus. The quantity that maximizes total surplus is Q1 procedures, which is less than Q2.c. The use of medical care is excessive in the sense that consumers get procedures whose value is less than the cost of producing them. As a result, the economy’s total surplus is reduced.d. To prevent this excessive use, the consumer must bear the marginal cost of the procedure. But this would require eliminating insurance. Another possibility would be that the insurance company, which pays most of the marginal cost of the procedure ($80, in this case) could decide whether the procedure should be performed. But the insurance company does not get the benefits of the procedure, so its decisions may not reflect the value to the consumer.。

蔡继明《微观经济学》章节题库详解(一般均衡与效率)【圣才出品】

第7章一般均衡与效率一、判断题1．局部均衡分析方法忽略了市场之间的相互影响，影响我们真正理解市场经济。

（）【答案】T【解析】每个市场之间都是相互联系的，只有理解了市场间的联系，才能真正理解市场经济。

2．契约曲线显示了所有不可能进行互利贸易的配置点。

（）【答案】F【解析】根据埃奇沃思盒形图，有效配置组合位于两种产品等产量线的切点上，这些点构成生产的契约曲线，由此可知，契约曲线显示了所有可能进行互利贸易的配置点。

3．不在生产契约线上的每一点所代表的投入组合都是无效率的。

（）【答案】T【解析】在生产契约线内的点代表资源没有得到充分的利用导致生产无效率，而在生产契约线外的点代表生产由于资源条件等所限达不到的生产点，所以不在生产契约线上的每一点所代表的投入组合都是无效率的。

4．只要生产是有效率的，产出组合就必然位于生产可能性曲线上的某一点。

（）【答案】T【解析】在生产契约线内的点代表资源没有得到充分的利用导致生产无效率，而在生产契约线外的点代表生产由于资源条件等所限达不到的生产点，所以有效率的生产所对应的产出组合必然位于生产可能性曲线上。

5．只有商品的边际转换率与边际替代率相等时，商品的生产结构才是最有效率的。

（）【答案】T【解析】生产与交换的帕累托最优条件是MRS XY A＝MRS XY B＝MRT XY，若边际转换率与边际替代率不等，则仍然存在帕累托改进的余地，即未达到最优的商品生产结构。

6．为了达到帕累托最优，必须使任何只消费两种商品的消费者所消费的这两种产品之间的边际替代率相等。

（）【答案】T【解析】交换的帕累托最优的条件是MRS XY A＝MRS XY B，即两种产品之间的边际替代率相等。

7．处于非帕累托最优位置的经济要达到帕累托最优经济的福利水平是不可能的。

（）【答案】F【解析】最优经济的福利水平不仅包括经济效率问题，而且还包括公平的实现问题。

8．帕累托最优的理论基础是序数效用理论，但对于基数效用理论也同样成立。

《微观经济学》综合习题第7章复习过程

微观经济学综合习题一第7章不完全竞争市场练习题1．下列各项中，错误的是（）A. 垄断厂商的平均收益曲线与需求曲线相重合B. 垄断厂商的边际收益曲线的斜率大于平均收益曲线的斜率C. 垄断厂商的边际收益大于平均收益D. 垄断厂商的边际收益小于平均收益2．在垄断厂商的短期均衡时，垄断厂商可以（）A. 亏损B. 利润为零C. 盈利D. 上述情况都可能存在3．弯折的需求曲线模型的假设条件是（）A. 行业内寡头厂商们之间是有勾结的B. 行业内某寡头厂商提价时，其他寡头厂商都会仿效C. 行业内某寡头厂商降价时，其他寡头厂商都会仿效D. 厂商可以任意进出市场4．垄断厂商的平均收益曲线与边际收益曲线均为直线时，平均收益曲线在Q轴上的截距是边际收益曲线在Q轴上的截距的（）A. 一倍B. 两倍C. 一半D. 四倍5．当垄断厂商的长期均衡产量上，可以有（）A. P大于LACB. P小于LACC. P等于最小的LACD. 以上情况都可能存在6．古诺模型达到均衡时，两厂商所占的市场份额为（）A. 1/2，1/2B. 1/3，1/3C. 1/3，2/3D. 3/5，2/57．如果在需求曲线某一点上的需求价格弹性e d＝5，商品的价格P＝6，则相应的边际收益MR为（）A. 7.5B. 24C. 1D. 4.88．古诺模型中，厂商以（）为目的A. 减少成本B. 利润最大化C. 价格稳定D. 扩大市场占有9．垄断竞争市场上厂商的短期均衡发生于（）A. 边际成本等于D需求曲线中产生的边际收益时B. 平均成本下降时C. d需求曲线与平均成本曲线相切时D. D需求曲线与d需求曲线相交，并有边际成本等于d需求曲线中产生的边际收益时10．当垄断市场的需求缺乏弹性时，MR为（）A. 负值B. 0C. 1D. 正值答案：C、D、C、B、A、B、D、B、D、A微观经济学综合习题二第七章不完全竞争的市场一、名词解释不完全竞争市场垄断市场生产集团理想的产量多余的生产能力寡头市场二、填空题1.如果需求曲线上某一点的需求的价格弹性e d=5，商品的价格P=6，则相应的边际收益MR=（）。

高鸿业版微观经济学练习题第七章_不完全竞争市场(参考练习与答案)

B. 不变成本，运输成本； D. 运输成本，可变成本；E. 不变成本，运输成本
8.219 下列哪种环境组合最有可能出现自然垄断？ A. 高不变成本，低运输成本；B. 高不变成本，高运输成本；C. 低不就成本，高运输成本；D.高可变成本，高运输成本；E．低可变成本，低运输成本。 8.220 买方垄断（Monophony）是（）。 A. 销售者的垄断；B. 购买者的垄断； C. 购买者和销售者都有垄断力； D. 寡头的另一种说法； E. 由垄断（Monopoly）拼写错误得出的名词。
8.18 当一个厂商对同一种物品向一个消费者集团收取的价格高于另一个消费者集团，或者实行“数量折扣” （即大量购买收取低价格）时，就存在价格歧视。 8.19 如果垄断者实行完全的价格歧视，它就可以获得所有消费者剩余。（）（）
8.110 为了对不同消费者集团实行价格歧视，垄断者就应该向需求富有弹性的消费者集团收取高价格。 8.111 对学生和有身份的人实行不同价格折扣的厂商不能实现利润最大化。（）（）
（2） Q=15
8.32 设垄断厂商的产品的需求函数为 P=12-0.4Q，总成本函数 TC=0.6Q +4Q+5，求：（1） Q 为多少时总利润最大，价格、总收益、及总利润各为多少？（2） Q 为多少时使总收益最大，与此相应的价格、总收益及总利润各为多少？（3） Q 为多少时使总收益最大且总利润π ≥10，与此相应的价格、总收益及总利润为多少？解：（1）总利润最大化的条件是 MC=MR。已知厂商的产品需求函数为 P=12-0.4Q，则 MR=12-0.8Q，又知 TC=0.6Q +4Q+5，则 MC=(TC)′=1.2Q+4。总利润最大时， MR=MC，即 12-0.8Q =1.2Q+4 ∴Q=4 把 Q=4 代入 P=12-0.4Q 中可得： P=12-0.4×4 = P=10.4 总收益 TR=PQ=10.4×4=41.6 总利润π =TR-TC=41.6-（0.6×4 +4×4+5）=11

微观经济学第七章答案

微观经济学第七章答案微观经济学第七章答案【篇一：微观经济学各校考研试题及答案整理第七章】>1概念题1.混合策略（mixed strategies）（中山大学2021试） 2．囚犯两难处境（人大1999试）3．纳什均衡（nash equilibrium）（华东师大2021试；南京大学2021试；中国海洋大学2002试；华中科大2002试；北师大2021试；厦门大学2021试；北航2021试；东华大学2021试） 4．占优均衡（dominant equilibrium）与纳什均衡（nashequilibrium）（北大1997；1998年试；中山大学2021试；东北财经大学2021试）5．双垄断（duopoly）（复旦大学1998试）6．折拐的需求曲线（kinky demand curve）（人大1998试） 7．串谋8．价格领导9．寡头价格（oligopoly price）10．贝叶斯纳什均衡（bayesian-nash equilibrium） 2 简答题1．解释卡特尔组织不稳定性的原因。

（北航2021试）2．说明纳什均衡与纳什定理的基本概念。

（南开大学2021试） 3．对比其他市场结构，说明不能建立一般的寡头模型的原因。

（天津财经学院2000试）4．请用博弈论思想简述中国为什么要加入世界贸易组织？（对外经贸大学2002试）5．两家计算机厂商a和b正计划推出用于办公室信息管理的网络系统。

各厂商都既可以开发一种高速、高质量的系统（h），也可以开发一种低速、低质量的系统（l）。

市场试究表明各厂商在不同策略下相应的利润由如下得益矩阵给出。

厂商b h lh 厂商a l（1）如果两厂商同时作决策且用极大化极小（低风险）策略，结果将是什么？（2）假设两厂商都试图最大化利润，且a先开始计划并实施，结果会怎样？如果b先开始，结果又会如何？（上海交大2021试）6．下面的矩阵表示两个厂商选择的策略的支付矩阵（单位：万元） b守约违约守约 a 违约（1）哪一种策略使a的最大可能损失为最小？b的是哪一种？（2）如果你是a，你会选择哪一种策略？为什么？如果a违约，b会做什么？如果b违约，a会做什么？（3）这一对策最可能出现的结果是什么？为什么？ 7．完全垄断与寡头垄断的区别。

厦门大学微观经济学第七章修改版

1.不同企业生产的产品具有差别，行业概念变得不明确 2.用生产集团的概念来代替行业概念 3.不能构造行业的需求曲线 4.研究代表性厂商的行为
二、垄断竞争厂商的需求曲线
1、垄断竞争厂商的需求曲线是一条向右下方倾斜的
曲线。
2、垄断竞争市场厂商所面临的需求曲线分两种，d需求曲线与D需求曲线。而其它市场厂商的需求曲线只有一种。
三级价格歧视的实施表现：在需求价格弹性小的市场提高产品价格，在需求价格弹性大的市场降低产品价格。
根据厂商利润最大化条件 MR1 MR2 MC 1 又MR1 P (1 ) 1 ed1 1 MR2 P2 (1 ) ed 2 1 1 P ed 2 1 所以 P2 1 1 ed1
第七章不完全竞争的市场
不完全竞争的市场
本章的主要内容是三种不完全竞争市场的价格和最佳产量点的决定，并就包括完全竞争市场在内的不同市场组织的经济效率进行比较。
垄断市场
分类
寡头市场
垄断竞争市场
第一节垄断
一、垄断市场的含义、条件及形成原因
1、含义：垄断市场是指整个行业中只有唯一的一个厂商的市场组织。 2、垄断市场的条件有三点条件：市场上只有唯一的一个厂商生产和销售商品其他任何厂商进入该行业都极为困难或不可能
例：电信运营业中的价格歧视
价格歧视程度一级价格歧视价格歧视策略大客户单独谈判定价靓号拍卖
二级价格歧视三级价格歧视
分段收费（超过一定量优惠）峰值定价产品差异定价不同套餐分别定价地区差异定价服务差异定价
来源：魏海峰（2005）
几个例子
家电下乡
Windows不同国家的不同价格麦当劳的价格策略（加一元汉堡加厚）

微观经济学作业(5-7章)

第一部分习题第五章成本理论一、名词解释1.机会成本；2.显性成本；3.隐性成本；4.经济利润；5.正常利润；6.边际成本；7.短期总成本；8.长期总成本；9.规模经济； 10.规模不经济； 11.范围经济； 12.学习效应。

二、简答题1.为何短期平均成本曲线的最低点一定在平均可变成本曲线最低点的右边?2.为什么在SAC最小时，SAC=SMC？3.短期平均成本曲线和长期平均成本曲线都呈U形，请解释它们形成U形的原因有何不同?三、论述题1. 简述影响长期平均成本变动的因素。

2.（1）假定某行业中所有企业的成本函数都是C＝Q＋100，而且产品的市场需求量为1000，这时在一个占有40％市场份额的企业与一个占有20％市场份额的企业之间，哪一个企业在成本上占有优势?为什么?（2）从长期角度看，企业规模是否处于规模不经济?为什么?（3）有人认为该行业中企业产量水平越高，企业的利润也越高，这种想法正确吗?3. 为什么长期总成本在每一产量水平上都小于等于短期总成本？四、计算题1.已知某企业的短期总成本函数STC（Q）＝5Q3－4Q2＋3Q＋50。

试求：（1）其中的可变成本和不变成本；（2）SAC（Q）、AFC（Q）、SMC（Q）的函数形式。

2.已知SMC＝9Q 2+4Q+5，TFC＝1000。

分别求STC、SAC、TVC和AVC的函数形式。

3.企业生产某产品的总固定成本为1000，平均总成本为50，平均可变成本是10，求企业现在的产量。

4.某厂商的短期生产函数为Q＝－0.1L3＋6L2＋12L，其中单位劳动工资为2，试求平均可变成本最小时的产量是多少？5.设某企业的生产函数为Q＝min（8L，4K），且P L＝2，P K＝3，试求当K＝10时的STC、SAC分别为多少？第六章完全竞争市场一、名词解释1. 完全竞争市场；2. 总收益；3. 平均收益；4. 边际收益；5. 收支相抵点；6. 停止营业点；7. 成本递增行业； 8. 成本递减行业； 9. 成本不变行业；10. 生产者剩余。

曼昆《经济学原理》第6版微观经济学分册第7章课后习题答案P157-P159

第三篇市场和福利第七章消费者、生产者与市场效率问题与应用1．Melissa用120美元购买了一个iPod，并得到了80美元的消费者剩余。

A．她的支付意愿是多少？答：消费者剩余等于支付意愿减去付出的价格。

因此，梅莉莎须支付200 美元($120 + $80)。

B．如果她在降价销售时买了售价为90美元的iPod，她的消费者剩余会是多少？答：此时，她的消费者剩余为：200-90 =110 美元。

C．如果iPod的价格是250美元，她的消费者剩余会是多少？答：如果iPod 的价格是250 美元，其价格大于梅莉莎的支付愿意，因此她不会再买，这时的消费者剩余就为零。

2．加利福尼亚早来的寒流使柠檬变酸。

柠檬市场上消费者剩余会有什么变动？柠檬水市场上消费者剩余会有什么变动？用图形说明你的答案。

答：柠檬变酸，消费者对柠檬的评价下降，需求曲线向左下方移动。

在其他条件不变的情况下，消费者剩余减少。

如图7－2(a)所示，柠檬质量下降，使需求曲线从D1下降到D 2，△APE是原先的消费者剩余，△A′P′E′是变动后的消费者剩余，△APE>△A′P′E′。

由于柠檬价格的下降，柠檬水的投入成本减少，柠檬水的价格也下降。

在其他条件不变的情况下，柠檬水市场上消费者剩余增加，如图7－2(b)所示。

图7－2 寒流的影响3．假设对法国面包的需求增加。

在法国面包市场上，生产者剩余会发生什么变动？在面粉市场上，生产者剩余会发生什么变动？用图形说明你的答案。

答：由于需求增加，在其他条件不变的情况下，法国面包的价格会上升，市场上的生产者剩余增加。

如图7 －3(a)，价格从P1 上升到P2 ，销量从Q 1上升到Q 2，生产者剩余从面积P1BE1增加到面积P2BE2 。

由于面包产量上升，它的生产要素面粉的需求量也会上升。

在其他条件不变的情况下，面粉价格上升，市场上的生产者剩余增加。

如图7－3(b)所示，生产者剩余从面积P1BE1增加到面积P2BE2 。

微观经济学课后习题答案第七章完整版

微观经济学课后习题答案第七章HEN system office room 【HEN16H-HENS2AHENS8Q8-HENH1688】第七章复习思考题参考答案1、为什么垄断厂商的需求曲线是向右下方倾斜的？并解释相应的TR 曲线、AR 曲线和MR 曲线的特征以及相互关系。

解答：垄断厂商所面临的需求曲线是向右下方倾斜的，其理由主要有两点：第一，垄断厂商所面临的需求曲线就是市场的需求曲线，而市场需求曲线一般是向右下方倾斜的，所以垄断厂商的需求量与价格成反方向的变化。

第二，假定厂商的销售量等于市场的需求量，那么，垄断厂商所面临的向右下方倾斜的需求曲线表示垄断厂商可以通过调整销售量来控制市场的价格，即垄断厂商可以通过减少商品的销售量来提高市场价格，也可以通过增加商品的销售量来降低市场价格。

关于垄断厂商的TR 曲线、AR 曲线和MR 曲线的特征以及相互关系，以图7-1加以说明：第一，平均收益AR 曲线与垄断厂商的向右下方倾斜的d 需求曲线重叠。

因为，在任何的销售量上，都是P=AR 。

第二，边际收益MR 曲线是向右下方倾斜的，且位置低于AR 曲线。

其原因在于AR 曲线是一条下降的曲线。

此外，在线性需求曲线的条件下，AR 曲线和MR 曲线的纵截距相同，而且MR 曲线的斜率的绝对值是AR 曲线的斜率的绝对值的两倍。

第三，由于MR 值是TR 曲线的斜率，即dQdTR MR =，所以，当MR>0时，TR 曲线是上升的；当MR ＜0时，TR 曲线是下降的；当MR=0时，TR 曲线达极大值。

图 7-1 垄断竞争厂商的AR 与TR 之间的关系2、根据图7-22中线性需求曲线d 和相应的边际收益曲线MR ，试求：（1）A 点所对应的MR 值；（2）B 点所对应的MR 值。

解答：（1）根据需求的价格点弹性的几何意义，可得A 点的需求的价格弹性为：25)515(=-=d e ，或者，2)23(2=-=d e ，根据)11(d e P MR -=，则A 点的MR 值为：MR=2×（2×1/2）=1。

曼昆微观经济学课后练习英文答案(第七章)

WHAT’S NEW IN THE SIXTH EDITION:There are no major changes to this chapter.LEARNING OBJECTIVES:By the end of this chapter, students should understand:➢ the link between buyers’ willingness to pay for a good and the demand curve.➢ how to define and measure consumer surplus.➢ the link between sellers’ costs of producing a good and the supply curve.➢ how to define and measure producer surplus.➢ that the equilibrium of supply and demand maximizes total surplus in a market.CONTEXT AND PURPOSE:Chapter 7 is the first chapter in a three-chapter sequence on welfare economics and market efficiency. Chapter 7 employs the supply and demand model to develop consumer surplus and producer surplus as a measure of welfare and market efficiency. These concepts are then utilized in Chapters 8 and 9 to determine the winners and losers from taxation and restrictions on international trade.The purpose of Chapter 7 is to develop welfare economics —the study of how the allocation ofresources affects economic well-being. Chapters 4 through 6 employed supply and demand in a positive framework, which focused on the question, “What is the equilibrium price and quantity in a market?” This chapter now addresses the normative question, “Is the equ ilibrium price and quantity in a market the best possible solution to the resource allocation problem, or is it simply the price and quantity thatbalance supply and demand?” Students will discover that under most circumstances the equilibrium price and quantity is also the one that maximizes welfare.7CONSUMERS, PRODUCERS, AND THE EFFICIENCY OF MARKETSKEY POINTS:• Consumer surplus equals buyers’ willingness to pay for a good minus the amount they actually pay for it, and it measures the benefit buyers get from participating in a market. Consumer surplus can be computed by finding the area below the demand curve and above the price.• Producer surplus equals the amount sellers receive for their goods minus their costs of production, and it measures the benefit sellers get from participating in a market. Producer surplus can be computed by finding the area below the price and above the supply curve.•An allocation of resources that maximizes the sum of consumer and producer surplus is said to be efficient. Policymakers are often concerned with the efficiency, as well as the equality, of economic outcomes.• The equilibrium of supply and demand maximizes the sum of consumer and producer surplus. That is,the invisible hand of the marketplace leads buyers and sellers to allocate resources efficiently.• Markets do not allocate resources efficiently in the presence of market failures such as market poweror externalities.CHAPTER OUTLINE:I. Definition of welfare economics: the study of how the allocation of resources affectseconomic well-being.II. Consumer SurplusA. Willingness to Pay1. Definition of willingness to pay: the maximum amount that a buyer will pay for agood.2. Example: You are auctioning a mint-condition recording of Elvis Presley’s first album. Fourbuyers show up. Their willingness to pay is as follows:If the bidding goes to slightly higher than $80, all buyers drop out except forJohn. Because John is willing to pay more than he has to for the album, hederives some benefit from participating in the market.3. Definition of consumer surplus: the amount a buyer is willing to pay for a goodminus the amount the buyer actually pays for it.4. Note that if you had more than one copy of the album, the price in the auction would end upbeing lower (a little over $70 in the case of two albums) and both John and Paul would gain consumer surplus.B. Using the Demand Curve to Measure Consumer Surplus1. We can use the information on willingness to pay to derive a demand curve for the rare ElvisPresley album.PriceBuyersQuantity DemandedMore than $100 None 0 $80 to $100 John1 $70 to $80 John, Paul2 $50 to $70 John, Paul, George3 $50 or lessJohn, Paul, George, Ringo42. At any given quantity, the price given by the demand curve reflects the willingness to pay ofthe marginal buyer . Because the demand curve shows the buyers’ willingness to pay, we can use the demand curve to measure consumer surplus.Figure 1 “This represents the demand curve for the time machine. Consumer surplus is the difference between what consumers are willing to pay and the amount they actually have to pay. The market price will deter mine who uses the time machine and how much surplus they keep.”“If the price of a time machine ride was $500, three rides would be sold—one to Scott, one to Carol, and one to Steve. Jeanne is not willing to pay $500, so she wouldn’t time travel.”“We c an calculate the consumer surplus of three time trips. Scott would pay $3,000 but only pays $500, leaving $2,500 of net benefits.” (Put these numbers on the board.) “Carol has net benefits of $2,000. Steve has $300 in net benefits. Adding up these net savings gives $4,800 in consumer surplus.”Points for DiscussionThe consumer surplus depends on a good’s selling price and the number of consumers who are willing to purchase the good at that price. The lower the price, the greater the consumer surplus.3. Consumer surplus can be measured as the area below the demand curve and above the price. C. How a Lower Price Raises Consumer Surplus1. As price falls, consumer surplus increases for two reasons.a. Those already buying the product will receive additional consumer surplus because theyare paying less for the product than before (area A on the graph).b. Because the price is now lower, some new buyers will enter the market and receiveconsumer surplus on these additional units of output purchased (area B on the graph).D. What Does Consumer Surplus Measure?1. Remember that consumer surplus is the difference between the amount that buyers arewilling to pay for a good and the price that they actually pay.2. Thus, it measures the benefit that consumers receive from the good as the buyersthemselves perceive it.Figure 2Figure 3It is important to stress that consumer surplus is measured in monetary terms. Consumer surplus gives us a way to place a monetary cost on inefficient market outcomes (due to government involvement or market failure).III. Producer SurplusA. Cost and the Willingness to Sell1. Definition of cost: the value of everything a seller must give up to produce a good .2. Example: You want to hire someone to paint your house. You accept bids for the work fromfour sellers. Each painter is willing to work if the price you will pay exceeds her opportunity cost. (Note that this opportunity cost thus represents willingness to sell.) The costs are:3. Bidding will stop when the price gets to be slightly below $600. All sellers will drop out exceptfor Grandma. Because Grandma receives more than she would require to paint the house, she derives some benefit from producing in the market.4. Definition of producer surplus: the amount a seller is paid for a good minus theseller’s cost of providing it.5. Note that if you had more than one house to paint, the price in the auction would end upbeing higher (a little under $800 in the case of two houses) and both Grandma and Georgia would gain producer surplus.ALTERNATIVE CLASSROOM EXAMPLE:Review the material on price ceilings from Chapter 6. Redraw the market for two-bedroom apartments in your town. Draw in a price ceiling below the equilibrium price.Then go through:▪ consumer surplus before the price ceiling is put into place. ▪ consumer surplus after the price ceiling is put into place.B. Using the Supply Curve to Measure Producer Surplus1. We can use the information on cost (willingness to sell) to derive a supply curve for housepainting services.Price Sellers Quantity Supplied$900 or more Mary, Frida, Georgia, Grandma 4$800 to $900 Frida, Georgia, Grandma 3$600 to $800 Georgia, Grandma 2$500 to $600 Grandma 1less than $500 None 02. At any given quantity, the price given by the supply curve represents the cost of the marginalseller. Because the supply curve shows the sellers’ cost (willingness to sell), we can use the supply curve to measure producer surplus.3. Producer surplus can be measured as the area above the supply curve and below the price. Figure 4Figure 5C. How a Higher Price Raises Producer Surplus1. As price rises, producer surplus increases for two reasons.a. Those already selling the product will receive additional producer surplus because theyare receiving more for the product than before (area C on the graph).b. Because the price is now higher, some new sellers will enter the market and receiveproducer surplus on these additional units of output sold (area D on the graph).D. Producer surplus is used to measure the economic well-being of producers, much like consumersurplus is used to measure the economic well-being of consumers.Figure 6ALTERNATIVE CLASSROOM EXAMPLE:Review the material on price floors from Chapter 6. Redraw the market for an agriculturalproduct such as corn. Draw in a price support above the equilibrium price.Then go through:▪ producer surplus before the price support is put in place.▪ producer surplus after the price support is put in place.Make sure that you discuss the cost of the price support to taxpayers.Pretty Woman, Chapter 6. Vivien (Julia Roberts) and Edward (Richard Gere)negotiate a price. Afterward, Vivien reveals she would have accepted a lower price,while Edward admits he would have paid more. If you have done a good job ofintroducing consumer and producer surplus, you will see the light bulbs go off aboveyour students’ heads as they watch this clip.IV. Market EfficiencyA. The Benevolent Social Planner1. The economic well-being of everyone in society can be measured by total surplus, which isthe sum of consumer surplus and producer surplus:Total Surplus = Consumer Surplus + Producer SurplusTotal Surplus = (Value to Buyers – Amount Paid by Buyers) + (Amount Received by Sellers – Cost to Sellers)Because the Amount Paid by Buyers = Amount Received by Sellers:2. Definition ofefficiency: the property of a resource allocation of maximizing thetotal surplus received by all members of society .3. Definition of equality: the property of distributing economic prosperity uniformlythe members of society .B. Evaluating the Market EquilibriumTotal Surplus = Value to Buyers Cost to Sellers Figure 7Now might be a good time to point out that many government policies involve atrade-off between efficiency and equity. When you evaluate government policies, like price ceilings or floors, you can explain them in terms of equity and efficiency.1. At the market equilibrium price:a. Buyers who value the product more than the equilibrium price will purchase the product;those who do not, will not purchase the product. In other words, the free marketallocates the supply of a good to the buyers who value it most highly, as measured bytheir willingness to pay.b. Sellers whose costs are lower than the equilibrium price will produce the product; thosewhose costs are higher, will not produce the product. In other words, the free marketallocates the demand for goods to the sellers who can produce it at the lowest cost.2. Total surplus is maximized at the market equilibrium.Figure 8a. At any quantity of output smaller than the equilibrium quantity, the value of the productto the marginal buyer is greater than the cost to the marginal seller so total surpluswould rise if output increases.b. At any quantity of output greater than the equilibrium quantity, the value of the productto the marginal buyer is less than the cost to the marginal seller so total surplus wouldrise if output decreases.3. Note that this is one of the reasons that economists believe Principle #6: Markets are usuallya good way to organize economic activity.It would be a good idea to remind students that there are circumstances when themarket process does not lead to the most efficient outcome. Examples includesituations such as when a firm (or buyer) has market power over price or when thereare externalities present. These situations will be discussed in later chapters.C. In the News: Ticket Scalping1. Ticket scalping is an example of how markets work to achieve an efficient outcome.2. This article from The Boston Globe descri bes economist Chip Case’s experience with ticketscalping.D. Case Study: Should There Be a Market in Organs?1. As a matter of public policy, people are not allowed to sell their organs.a. In essence, this means that there is a price ceiling on organs of $0.b. This has led to a shortage of organs.2. The creation of a market for organs would lead to a more efficient allocation of resources,but critics worry about the equity of a market system for organs.V. Market Efficiency and Market FailureA. To conclude that markets are efficient, we made several assumptions about how markets worked.1. Perfectly competitive markets.2. No externalities.B. When these assumptions do not hold, the market equilibrium may not be efficient.C. When markets fail, public policy can potentially remedy the situation.SOLUTIONS TO TEXT PROBLEMS:Quick Quizzes1. Figure 1 shows the demand curve for turkey. The price of turkey is P1 and the consumersurplus that results from that price is denoted CS. Consumer surplus is the amount a buyer iswilling to pay for a good minus the amount the buyer actually pays for it. It measures thebenefit to buyers of participating in a market.Figure 1 Figure 22. Figure 2 shows the supply curve for turkey. The price of turkey is P1 and the producersurplus that results from that price is denoted PS. Producer surplus is the amount sellers arepaid for a good minus the sellers’ cost of providing it (measured by the supply curve). Itmeasures the benefit to sellers of participating in a market.Figure 33. Figure 3 shows the supply and demand for turkey. The price of turkey is P1, consumersurplus is CS, and producer surplus is PS. Producing more turkeys than the equilibriumquantity would lower total surplus because the value to the marginal buyer would be lowerthan the cost to the marginal seller on those additional units.Questions for Review1. The price a buyer is willing to pay, consumer surplus, and the demand curve are all closelyrelated. The height of the demand curve represents the willingness to pay of the buyers.Consumer surplus is the area below the demand curve and above the price, which equals theprice that each buyer is willing to pay minus the price actually paid.2. Sellers' costs, producer surplus, and the supply curve are all closely related. The height of thesupply curve represents the costs of the sellers. Producer surplus is the area below the priceand above the supply curve, which equals the price received minus each seller's costs ofproducing the good.Figure 43. Figure 4 shows producer and consumer surplus in a supply-and-demand diagram.4. An allocation of resources is efficient if it maximizes total surplus, the sum of consumersurplus and producer surplus. But efficiency may not be the only goal of economicpolicymakers; they may also be concerned about equity the fairness of the distribution ofwell-being.5. The invisible hand of the marketplace guides the self-interest of buyers and sellers intopromoting general economic well-being. Despite decentralized decision making and self-interested decision makers, free markets often lead to an efficient outcome.6. Two types of market failure are market power and externalities. Market power may causemarket outcomes to be inefficient because firms may cause price and quantity to differ fromthe levels they would be under perfect competition, which keeps total surplus from beingmaximized. Externalities are side effects that are not taken into account by buyers and sellers.As a result, the free market does not maximize total surplus.Problems and Applications1. a. Consumer surplus is equal to willingness to pay minus the price paid. Therefore,Melissa’s willingness to pay must be $200 ($120 + $80).b. Her consumer surplus at a price of $90 would be $200 − $90 = $110.c. If the price of an iPod was $250, Melissa would not have purchased one because theprice is greater than her willingness to pay. Therefore, she would receive no consumersurplus.2. If an early freeze in California sours the lemon crop, the supply curve for lemons shifts to theleft, as shown in Figure 5. The result is a rise in the price of lemons and a decline inconsumer surplus from A + B + C to just A. So consumer surplus declines by the amount B +C.Figure 5 Figure 6In the market for lemonade, the higher cost of lemons reduces the supply of lemonade, asshown in Figure 6. The result is a rise in the price of lemonade and a decline in consumersurplus from D + E + F to just D, a loss of E + F. Note that an event that affects consumersurplus in one market often has effects on consumer surplus in other markets.3. A rise in the demand for French bread leads to an increase in producer surplus in the marketfor French bread, as shown in Figure 7. The shift of the demand curve leads to an increased price, which increases producer surplus from area A to area A + B + C.Figure 7The increased quantity of French bread being sold increases the demand for flour, as shown in Figure 8. As a result, the price of flour rises, increasing producer surplus from area D to D + E + F. Note that an event that affects producer surplus in one market leads to effects on producer surplus in related markets.Figure 84. a. Bert’s demand schedule is:Price Quantity DemandedMore than $7 0$5 to $7 1$3 to $5 2$1 to $3 3$1 or less 4Bert’s demand curve is shown in Figure 9.Figure 9b. When the price of a bottle of water is $4, Bert buys two bottles of water. His consumersurplus is shown as area A in the figure. He values his first bottle of water at $7, butpays only $4 for it, so has consumer surplus of $3. He values his second bottle of water at $5, but pays only $4 for it, so has consumer surplus of $1. Thus Bert’s total consumer surplus is $3 + $1 = $4, which is the area of A in the figure.c. When the price of a bottle of water falls from $4 to $2, Bert buys three bottles of water,an increase of one. His consumer surplus consists of both areas A and B in the figure, an increase in the amount of area B. He gets consumer surplus of $5 from the first bottle($7 value minus $2 price), $3 from the second bottle ($5 value minus $2 price), and $1 from the third bottle ($3 value minus $2 price), for a total consumer surplus of $9. Thus consumer surplus rises by $5 (which is the size of area B) when the price of a bottle ofwater falls from $4 to $2.5. a. Ernie’s supply schedule for water is:Price Quantity SuppliedMore than $7 4$5 to $7 3$3 to $5 2$1 to $3 1Less than $1 0Ernie’s supply curve is shown in Figure 10.Figure 10b. When the price of a bottle of water is $4, Ernie sells two bottles of water. His producersurplus is shown as area A in the figure. He receives $4 for his first bottle of water, but itcosts only $1 to produce, so Ernie has producer surplus of $3. He also receives $4 for his second bottle of water, which costs $3 to produce, so he has producer surplus of $1.Thus Ernie’s total producer surplus is $3 + $1 = $4, which is the area of A in the figure.c. When the price of a bottle of water rises from $4 to $6, Ernie sells three bottles of water,an increase of one. His producer surplus consists of both areas A and B in the figure, anincrease by the amount of area B. He gets producer surplus of $5 from the first bottle($6 price minus $1 cost), $3 from the second bottle ($6 price minus $3 cost), and $1from the third bottle ($6 price minus $5 price), for a total producer surplus of $9. Thusproducer surplus rises by $5 (which is the size of area B) when the price of a bottle ofwater rises from $4 to $6.6. a. From Ernie’s supply schedule and Bert’s demand schedule, the quantity demanded andsupplied are:Price Quantity Supplied Quantity Demanded$2 1 3$4 2 2$6 3 1Only a price of $4 brings supply and demand into equilibrium, with an equilibriumquantity of two.b. At a price of $4, consumer surplus is $4 and producer surplus is $4, as shown inProblems 3 and 4 above. Total surplus is $4 + $4 = $8.c. If Ernie produced one less bottle, his producer surplus would decline to $3, as shown inProblem 4 above. If Bert consumed one less bottle, his consumer surplus would declineto $3, as shown in Problem 3 above. So total surplus would decline to $3 + $3 = $6.d. If Ernie produced one additional bottle of water, his cost would be $5, but the price isonly $4, so his producer surplus would decline by $1. If Bert consumed one additionalbottle of water, his value would be $3, but the price is $4, so his consumer surplus would decline by $1. So total surplus declines by $1 + $1 = $2.7. a. The effect of falling production costs in the market for stereos results in a shift to theright in the supply curve, as shown in Figure 11. As a result, the equilibrium price ofstereos declines and the equilibrium quantity increases.Figure 11b. The decline in the price of stereos increases consumer surplus from area A to A + B + C+ D, an increase in the amount B + C + D. Prior to the shift in supply, producer surpluswas areas B + E (the area above the supply curve and below the price). After the shift in supply, producer surplus is areas E + F + G. So producer surplus changes by the amountF +G – B, which may be positive or negative. The increase in quantity increasesproducer surplus, while the decline in the price reduces producer surplus. Becauseconsumer surplus rises by B + C + D and producer surplus rises by F + G – B, totalsurplus rises by C + D + F + G.c. If the supply of stereos is very elastic, then the shift of the supply curve benefitsconsumers most. To take the most dramatic case, suppose the supply curve werehorizontal, as shown in Figure 12. Then there is no producer surplus at all. Consumerscapture all the benefits of falling production costs, with consumer surplus rising fromarea A to area A + B.Figure 128. Figure 13 shows supply and demand curves for haircuts. Supply equals demand at a quantityof three haircuts and a price between $4 and $5. Firms A, C, and D should cut the hair of Ellen, Jerry, and Phil. Oprah’s willingness to pay is too low and firm B’s costs are too high, so they do not participate. The maximum total surplus is the area between the demand and supply curves, which totals $11 ($8 value minus $2 cost for the first haircut, plus $7 value minus $3 cost for the second, plus $5 value minus $4 cost for the third).Figure 139. a. The effect of falling production costs in the market for computers results in a shift to theright in the supply curve, as shown in Figure 14. As a result, the equilibrium price ofcomputers declines and the equilibrium quantity increases. The decline in the price ofcomputers increases consumer surplus from area A to A + B + C + D, an increase in the amount B + C + D.Figure 14 Figure 15Prior to the shift in supply, producer surplus was areas B + E (the area above the supply curve and below the price). After the shift in supply, producer surplus is areas E + F + G.So producer surplus changes by the amount F + G – B, which may be positive ornegative. The increase in quantity increases producer surplus, while the decline in theprice reduces producer surplus. Because consumer surplus rises by B + C + D andproducer surplus rises by F + G – B, total surplus rises by C + D + F + G.b. Because typewriters are substitutes for computers, the decline in the price of computersmeans that people substitute computers for typewriters, shifting the demand fortypewriters to the left, as shown in Figure 15. The result is a decline in both theequilibrium price and equilibrium quantity of typewriters. Consumer surplus in thetypewriter market changes from area A + B to A + C, a net change of C – B. Producersurplus changes from area C + D + E to area E, a net loss of C + D. Typewriterproducers are sad about technological advances in computers because their producersurplus declines.c. Because software and computers are complements, the decline in the price and increasein the quantity of computers means that the demand for software increases, shifting the demand for software to the right, as shown in Figure 16. The result is an increase in both the price and quantity of software. Consumer surplus in the software market changesfrom B + C to A + B, a net change of A – C. Producer surplus changes from E to C + D + E, an increase of C + D, so software producers should be happy about the technological progress in computers.Figure 16d. Yes, this analysis helps explain why Bill Gates is one the world’s richest people, becausehis company produces a lot of software that is a complement with computers and therehas been tremendous technological advance in computers.10. a. With Provider A, the cost of an extra minute is $0. With Provider B, the cost of an extraminute is $1.b. With Provider A, my friend will purchase 150 minutes [= 150 – (50)(0)]. With Provider B,my friend would purchase 100 minutes [= 150 – (50)(1)].c. With Provider A, he would pay $120. The cost would be $100 with Provider B.Figure 17d. Figure 17 shows the friend’s demand. With Provider A, he buys 150 minu tes and hisconsumer surplus is equal to (1/2)(3)(150) – 120 = 105. With Provider B, his consumersurplus is equal to (1/2)(2)(100) = 100.e. I would recommend Provider A because he receives greater consumer surplus.11. a. Figure 18 illustrates the demand for medical care. If each procedure has a price of $100,quantity demanded will be Q1 procedures.Figure 18b. If consumers pay only $20 per procedure, the quantity demanded will be Q2 procedures.Because the cost to society is $100, the number of procedures performed is too large to maximize total surplus. The quantity that maximizes total surplus is Q1 procedures, which is less than Q2.c. The use of medical care is excessive in the sense that consumers get procedures whosevalue is less than t he cost of producing them. As a result, the economy’s total surplus is reduced.d. To prevent this excessive use, the consumer must bear the marginal cost of theprocedure. But this would require eliminating insurance. Another possibility would be that the insurance company, which pays most of the marginal cost of the procedure ($80, in this case) could decide whether the procedure should be performed. But the insurance company does not get the benefits of the procedure, so its decisions may not reflect the value to the consumer.。

高鸿业微观经济学(第5版)课后习题答案第七章

第七章不完全竞争的市场1. 根据图7—1(即教材第205页的图7—18)中线性需求曲线d和相应的边际收益曲线MR，试求：图7—1(1)A点所对应的MR值；(2)B点所对应的MR值。

解答：(1)根据需求的价格点弹性的几何意义，可得A点的需求的价格弹性为e d＝eq \f(15－5,5)＝2或者e d＝eq \f(2,3－2)＝2再根据公式MR＝P eq \b\lc$\rc$(\a\vs4\al\co1(1－\f(1,e d)))，则A点的MR值为MR＝2×eq \b\lc$\rc$(\a\vs4\al\co1(1－\f(1,2)))＝1(2)与(1)类似，根据需求的价格点弹性的几何意义，可得B点的需求的价格弹性为e d＝eq \f(15－10,10)＝eq \f(1,2)或者e d＝eq \f(1,3－1)＝eq \f(1,2)再根据公式MR＝P eq \b\lc$\rc$(\a\vs4\al\co1(1－\f(1,e d)))，则B点的MR值为MR＝1×eq \b\lc$\rc$(\a\vs4\al\co1(1－\f(1,1/2)))＝－12. 图7—2(即教材第205页的图7—19)是某垄断厂商的长期成本曲线、需求曲线和收益曲线。

试在图中标出：(1)长期均衡点及相应的均衡价格和均衡产量；(2)长期均衡时代表最优生产规模的SAC曲线和SMC曲线；(3)长期均衡时的利润量。

图7—2解答：本题的作图结果如图7—3所示：图7—3(1)长期均衡点为E点，因为在E点有MR＝LMC。

由E点出发，均衡价格为P0，均衡数量为Q0。

(2)长期均衡时代表最优生产规模的SAC曲线和SMC曲线如图7—3所示。

在Q0的产量上，SAC曲线和LAC曲线相切；SMC曲线和LMC曲线相交，且同时与MR曲线相交。

(3)长期均衡时的利润量由图7—3中阴影部分的面积表示，即π＝[AR(Q0)－SAC(Q0)]·Q 0。

蔡继明《微经济学(第2版)》课后习题详解(第7章一般均衡与效率)

蔡继明《微观经济学（第2版）第7章一般均衡与效率跨考网独家整理最全经济学考研真题，经济学考研课后习题解析资料库，您可以在这里查阅历年经济学考研真题，经济学考研课后习题，经济学考研参考书等内容，更有跨考考研历年辅导的经济学学哥学姐的经济学考研经验，从前辈中获得的经验对初学者来说是宝贵的财富，这或许能帮你少走弯路，躲开一些陷阱。

以下内容为跨考网独家整理，如您还需更多考研资料，可选择经济学一对一在线咨询进行咨询。

1．解释下列基本概念：一般均衡、契约曲线、生产可能性曲线、边际转换率、帕累托标准、经济效率、社会福利函数。

答：略。

2．假定两个人的偏好完全相同，交换的契约曲线会不会是一条直线？试举例说明。

答：（1）如果两个人的偏好完全相同，且无差异曲线具有严格凹的良好性状时，交换的契约曲线是一条直线。

在交换的埃奇渥斯盒状图中，任意一点，如果它处在两个消费者的两条无差异曲线的切点上，则它就是帕累托最优状态，并称之为交换的帕累托最优状态。

在这种情况下，不存在有帕累托改进的余地，即任何改变都不能使至少一个人的状况变好而没有人的状况变坏。

无差异曲线的切点不只是一个。

所有无差异曲线的切点的轨迹构成曲线，称为交换的契约曲线（或效率曲线），它表示两种产品在两个消费者之间的所有最优分配（即帕累托最优状态）的集合。

根据题意，对于两个人，两种商品的经济，可通过给定B u ，使A u 极大化来求契约曲线，即：12max A A A u q q α=使得：()()000121122B B B A A u q q q q qq ββ==--构造拉格朗日函数：()()00121122a A A A A Bq q q q qq u βϕλ⎡⎤=+-+-⎢⎥⎣⎦令一阶偏导数为零：()()11002112210a A A A A A q q q q q q q βϕαλβ--∂=--+=∂ ① ()011120a A A A q q q q βϕλ∂=--=∂ ② ()()000011220A B q q q q u βϕλ∂=---=∂ ③ 由①②得：()()()100111221211a A A A A AA q q qq q qq q q βαββα----=-于是，所求契约方程为：()2220111A A A A q q q q q q βα-=-或0021121212A A A A A A q q q q q q q q ααββ-=-。

平狄克《微观经济学》(第7版)习题详解(第7章生成成本)

平狄克《微观经济学》（第7版）第7章生产成本课后复习题详解跨考网独家整理最全经济学考研真题，经济学考研课后习题解析资料库，您可以在这里查阅历年经济学考研真题，经济学考研课后习题，经济学考研参考书等内容，更有跨考考研历年辅导的经济学学哥学姐的经济学考研经验，从前辈中获得的经验对初学者来说是宝贵的财富，这或许能帮你少走弯路，躲开一些陷阱。

以下内容为跨考网独家整理，如您还需更多考研资料，可选择经济学一对一在线咨询进行咨询。

1．某公司支付给会计人员10000美元的年薪，这笔费用是一项经济成本吗？答：这笔费用是一项经济成本。

经济成本是显性成本和隐性成本之和。

显性成本指实际支出，所有涉及到货币交易行为的成本都属于显性成本。

隐性成本是一种经济成本，不涉及到货币交易行为，但涉及到生产中所使用的资源的成本。

当一个公司支付给会计人员10000美元年薪时，这是一笔货币交易，这笔费用是会计人员用劳动换来的收入。

因此，这笔费用属于经济成本中的显性成本。

2．某小零售店女店主自己做账，你将如何计算她工作的机会成本？答：该店主自己做账的机会成本是：她利用做账的时间和精力做其他事情时所能获得的最大收入。

根据机会成本的定义，如果该小零售店女店主不是自己做账，她可以在这段时间里做其他的事情，例如做小生意或者参加一些休闲活动。

那么，女店主自己做账的机会成本就是她用于做账的时间做其他事情时所能获得的最大收入。

3．解释以下说法正确与否：（1）如果一家企业的拥有者不给自己支付工资，则会计成本为零，而经济成本为正。

（2）会计利润为正的企业不一定经济利润也为正。

（3）企业雇佣了一些目前处于失业状态的工人，则其使用这些工人服务的机会成本为零。

答：（1）正确。

因为这里不存在货币交易，所以不存在会计成本（或显性成本）。

但是，因为企业的拥有者可以受雇于其他企业，因而存在经济成本。

经济成本为正，反映了此人工作时间的机会成本。

（2）正确。

会计利润仅考虑显性成本。

西方经济学(微观经济学)课后练习答案第七章

微观第七章习题一、名词解释完全垄断市场垄断竞争市场寡头市场价格歧视博弈纳什均衡占优策略均衡二、选择题1、对于垄断厂商来说，（）。

A、提高价格一定能够增加收益；B、降低价格一定会减少收益；C、提高价格未必会增加收益，降低价格未必会减少收益；D、以上都不对。

2、完全垄断的厂商实现长期均衡的条件是（）。

A、MR=MC；B、MR=SMC=LMC；C、MR=SMC=LMC=SAC；D、MR=SMC=LMC=SAC=LAC。

3、完全垄断厂商的总收益与价格同时下降的前提条件是（）。

A、Ed>1；B、Ed<1；C、Ed=1；D、Ed=0。

4、完全垄断厂商的产品需求弹性Ed=1时（）。

A、总收益最小；B、总收益最大；C、总收益递增；D、总收益递减。

5、完全垄断市场中如果A市场的价格高于B市场的价格，则（）A、A市场的需求弹性大于B市场的需求弹性；B、A市场的需求弹性小于B市场的需求弹性；C、A市场的需求弹性等于B市场的需求弹性；D、以上都对。

6、以下关于价格歧视的说法不正确的是（）。

A、价格歧视要求垄断者能根据消费者的支付意愿对其进行划分；B、一级价格歧视引起无谓损失；C、价格歧视增加了垄断者的利润；D、垄断者进行价格歧视，消费者就必定不能进行套利活动。

7、垄断竞争的厂商短期均衡时，（）。

A、一定能获得差额利润；B、一定不能获得经济利润；C、只能得到正常利润；D、取得经济利润、发生亏损和获得正常利润都有可能。

8、垄断竞争厂商长期均衡点上，长期平均成本曲线处于（ B ）A、上升阶段B、下降阶段C、水平阶段D、以上三种情况都有可能9、垄断竞争厂商实现最大利润的途径有：（ D ）A、调整价格从而确定相应产量B、品质竞争C、广告竞争D、以上途径都可能用10、按照古诺模型下列哪一说法不正确，（）。

A、双头垄断者没有认识到他们的相互依耐性；B、每一个寡头都认定对方的产量保持不变；C、每一个寡头垄断者都假定对方价格保持不变；D、均衡的结果是稳定的。

蔡继明微观经济学习题第7章

7 一般均衡与效率7。

1 判断题7。

11 局部均衡分析方法忽略了市场之间的相互影响，影响我们真正理解市场经济. （) 7.12 契约曲线显示了所有的可能进行互利贸易的配置点. （) 7。

13 不在生产契约线上的每一点所代表的投入组合都是无效率的. （）7。

14 只要生产是有效率的,产出组合就必然位于生产可能性曲线上的某一点. （）7。

15 只有商品的边际转换率与边际替代率相等时，商品的生产结构才是最有效率的。

（）7。

16 为了达到帕累托最优，必须使任何只消费两种商品的消费者所消费的这两种产品之间的边际替代率相等。

( ）7。

17 处于非帕累托最优位置的经济要达到帕累托最优经济的福利水平是不可能的。

( ）7.18 帕累托最优的理论基础是序数效用理论，但对于基数效用理论也同样成立. ( ）7。

19 现代经济学所说的最有经济效率的状态,一般就是指帕累托最优状态. （）7。

110 从社会观点来看，契约曲线上所有的点都是理想的. （）7.111 消费者均衡条件满足后，帕累托状态也达到最优。

( ）7。

112 社会福利函数应该能够代表全社会所有人对福利的判断。

（) 7。

113 福利经济学第一定理即任何竞争性市场均衡都是有效率的。

（) 7.114 如果个人偏好是凸型的，则每一个帕累托有效配置对于商品的某个初始禀赋来说，是一个竞争性均衡。

（）7.115 资源配置如果无法做到改善某些人的福利,同时又不损害其他人的福利,从经济学意义上看就是有效率的. （）7。

116 在不存在垄断的情况下，没有管制的市场将使收入分配均等。

（）7。

117 竞争性均衡必然是公平的。

（) 7.118 如果两种商品之间的边际转换率不是对所有消费这两种商品的消费者来说都等于它们之间的边际替代率,那种两种商品中至少有一种不是有效地生产出来的。

( ）7.119 从埃奇斯盒状图中某一初始禀赋开始,如果通过讨价还价达到的自由交易契约是符合帕累托最适度状态所要求的，那么该交换契约可以位于契约曲线的任何地方。

平狄克《微观经济学》(第7版)习题详解(第7章生成成本)

平狄克《微观经济学》(第7版)习题详解(第7章生成成本)Born to win经济学考研交流群 <<平狄克《微观经济学》（第7版）第7章生产成本课后复习题详解跨考网独家整理最全经济学考研真题，经济学考研课后习题解析资料库，您可以在这里查阅历年经济学考研真题，经济学考研课后习题，经济学考研参考书等内容，更有跨考考研历年辅导的经济学学哥学姐的经济学考研经验，从前辈中获得的经验对初学者来说是宝贵的财富，这或许能帮你少走弯路，躲开一些陷阱。

以下内容为跨考网独家整理，如您还需更多考研资料，可选择经济学一对一在线咨询进行咨询。

1．某公司支付给会计人员10000美元的年薪，这笔费用是一项经济成本吗？答：这笔费用是一项经济成本。

经济成本是显性成本和隐性成本之和。

显性成本指实际支出，所有涉及到货币交易行为的成本都属于显性成本。

隐性成本是一种经济成本，不涉及到货币交易行为，但涉及到生产中所使用的资源的成本。

当一个公司支付给会计人员10000美元年薪时，这是一笔货币交易，这笔费用是会计人员用劳动换来的收入。

因此，这笔费用属于经济成本中的显性成本。

根据机会成本的定义，如果该小零售店女店主不是自己做账，她可以在这段时间里做其他的事情，例如做小生意或者参加一些休闲活动。

那么，女店主自己做账的机会成本就是她用于做账的时间做其他事情时所能获得的最大收入。

3．解释以下说法正确与否：（1）如果一家企业的拥有者不给自己支付工资，则会计成本为零，而经济成本为正。

（2）会计利润为正的企业不一定经济利润也为正。

（3）企业雇佣了一些目前处于失业状态的工人，则其使用这些工人服务的机会成本为零。

答：（1）正确。

因为这里不存在货币交易，所以不存在会计成本（或显性成本）。

但是，因为企业的拥有者可以受雇于其他企业，因而存在经济成本。

高鸿业微观第七版第7章习题参考答案

π＝TR－TC＝[AR(Q0)－SAC(Q0)]Q。
第 1 页共 13 页
3.【答案】由于垄断厂商所面临的需求曲线向右下方倾斜，导致了垄断厂商所面临的需求曲线
的位置高于边际收益 MR 曲线的位置，即总有 P > MR。所以，在垄断厂商实现 MR = MC 利润最大化均衡时，必有 P > MC。
7.【答案】
（1）由长期总成本函数 LTC＝0.001Q3－0.51Q2＋200Q，可得：
LAC＝0.001Q2－0.51Q＋200。
垄断竞争厂商长期均衡时，利润为零，此时，D 与 LAC 相交，即有：AR＝P＝LAC，
代入相关参数可得：238－0.5Q＝0.001Q2－0.51Q＋200
解得 Q1＝－190（舍去），Q2＝200。
第 2 页共 13 页
所以，当该垄断厂商实现利润最大化时，其产量 Q＝2.5，价格 P=7，收益 TR ＝17.5，利润 л＝4.25 （2）由已知条件可得 MR＝8－0.8Q，令 MR＝8－0.8Q＝0，解得 Q＝10
且 dTR 0.8 0 dQ
所以，当 Q＝10 时，TR 值达最大值。以 Q＝10 代入反需求函数 P＝8－0.4Q，得：P＝8－0.4×10＝4 则有：TR＝PQ＝4×10＝40 л ＝TR－TC=PQ－TC
在经济学分析中，通常把厂商均衡时 P 与 MC 之间的大小比较作为衡量市场经济效率的一个标准。在完全竞争市场条件下，厂商所面临的需求曲线与边际收益 MR 曲线重合，即有 P＝MR，所以，在完全竞争厂商实现 MR＝MC 利润最大化均衡时，必有 P＝MC。在完全竞争厂商均衡的 P = MC 条件下，厂商销售产品的价格刚好等于生产的边际成本，并实现了全部的消费者剩余和生产者剩余。而在垄断厂商均衡的 P > MC 条件下，厂商销售产品的价格大于等于生产的边际成本，且减少了消费者剩余和生产者剩余，形成了社会福利的“无谓损失”。

《微观经济学》(刘天祥版)第七章参考答案

《微观经济学》第七章参考答案一、略二、选择题CBDDC CABDD BB1、C.2、B.3、D.完全垄断厂商无论是短期还是长期，其均衡时的产量都是由MR=MC决定的。

4、D.5、C.6、C.7、A.8、B.完全垄断厂商实行价格歧视是在需求价格弹性小的市场上提高价格，而在需求价格弹性大的市场上降低价格。

9、D. 垄断势力的存在使厂商可以维持低产高价，从而使资源配置无效率。

10、B11、B.由于总收益下降，则边际收益为负。

且11d MR PE⎛⎫=-⎪⎝⎭12、B.由11dMR PE⎛⎫=-⎪⎝⎭，可知，当1dE=时，MR=0，所以此时总收益最大。

三、判断题√×√√√√××1、√。

对于垄断厂商有P=AR为需求曲线，而边际收益曲线MR总是位于需求曲线的下方。

2、×。

垄断厂商没有确定的供给曲线。

3、√。

一级价格歧视下，虽然所有的消费者剩余都被厂商剥夺了，但是其均衡的价格和产量与完全竞争下的均衡价格和产量一样，所以其资源配置是有效率的。

4、√5、√6、√7、×。

垄断竞争厂商的边际收益曲线是根据其相应的主观需求曲线得到的。

8、×。

短期内垄断厂商既可能获得经济利润也可能经济利润为0，还可能出现亏损。

四、计算题1、总利润最大化条件为：MC=MR；已知需求函数P=12-0.4Q可推知：MR=12-0.8Q；又有TC函数可以推知：MC=1.2Q+4；利润最大化，即1.2Q+4=12-0.8Q ，可得Q=4；将Q=4代入P=12-0.4Q ，得P=10.4；总收益：TR=P*Q=10.4×4=41.6；总利润：π=TR -TC=11；2、（1）垄断厂商利润最大化：MR=MC ，已知TC 可得MC=Q+10；又TR=（90-0.5Q ）Q 可得MR=90-Q ；于是：MR=MC 即Q+10=90-Q ，解之Q=40；将Q=40带入需求函数，解之P=70；利润π=TR -TC=1600（2）当P=55时，即90-0.5Q=55 得，Q=70；当Q=70时，TC=3150；TR=P*Q=3850π=TR -TC=700；（3）假设国家最高限价P=50，这实际上是对垄断厂商采取了边际成本定价的原则即P=MC ；此时厂商提供的产量为Q=40；厂商的利润为π=TR -TC=800；然而此时市场的需求根据需求函数计算得Q=80，故会出现市场供不应求的局面。

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