英文微观经济学试题及答案

英文微观经济学试题及答案
一、选择题（每题2分，共20分）
1. Which of the following is not a characteristic of a perfectly competitive market?
A. Many buyers and sellers
B. Homogeneous products
C. Free entry and exit
D. Monopoly power
Answer: D
2. The law of diminishing returns states that:
A. The total product of labor increases as more labor is added
B. The marginal product of labor eventually decreases as more labor is added
C. The average product of labor is always higher than the marginal product
D. The marginal product of labor is always higher than the average product
Answer: B
3. In the short run, a firm in a perfectly competitive market will shut down if:
A. Total revenue is greater than total variable cost
B. Total revenue is less than total cost
C. Total revenue is less than total variable cost
D. Total revenue is less than average total cost
Answer: C
4. The demand for a good is likely to be more elastic when:
A. The good has many close substitutes
B. The good is a luxury item
C. The good is a necessity
D. The good represents a small proportion of consumer's income
Answer: A
5. The consumer surplus is the difference between:
A. The maximum price a consumer is willing to pay and the market price
B. The market price and the minimum price a consumer is willing to pay
C. The maximum price a consumer is willing to pay and the minimum price a consumer is willing to pay
D. The minimum price a consumer is willing to pay and the market price
Answer: A
...（此处省略其他选择题）
二、简答题（每题10分，共30分）
1. Explain the concept of price elasticity of demand and its
determinants.
Answer: Price elasticity of demand measures the responsiveness of the quantity demanded of a good to a change in its price. It is calculated as the percentage change in quantity demanded divided by the percentage change in price. The determinants of price elasticity include the availability of substitutes, the proportion of income spent on the good, the necessity of the good, and the time period over which the demand is being considered.
2. What is the difference between a normal good and an
inferior good?
Answer: A normal good is a good for which the demand increases as income increases, while the demand for an
inferior good decreases as income increases. This is because normal goods are typically considered desirable or of higher quality, while inferior goods are seen as lower quality substitutes that consumers prefer to avoid as their income increases.
3. Define the law of supply and give an example.
Answer: The law of supply states that, all else being equal, the quantity supplied of a good will increase as the price of the good increases, and decrease as the price of the good decreases. An example of this would be the supply of oil; if the price of oil rises, producers are more likely to increase production and supply more oil to the market.
三、计算题（每题25分，共50分）
1. A firm has the following total cost function: TC = 0.5Q^2 - 4Q + 100. Calculate the firm's average total cost (ATC) and marginal cost (MC) at the quantity level of Q = 50.
Answer:
To find the average total cost (ATC), we divide the total cost (TC) by the quantity (Q):
\[ ATC = \frac{TC}{Q} = \frac{0.5Q^2 - 4Q + 100}{Q} \]
At Q = 50:
\[ ATC = \frac{0.5(50)^2 - 4(50) + 100}{50} = \frac{1250}{50} = 25 \]
The marginal cost (MC) is the derivative of the total cost function with respect to quantity:
\[ MC = \frac{dTC}{dQ} = 0.5 \times 2Q - 4 \]
At Q = 50:
\[ MC = 0.5 \times 2 \times 50 - 4 = 50 - 4 = 46 \]
2. A monopolist faces the demand function P = 100 - 2Q and has a total cost function TC = 10Q. Calculate the profit-maximizing level of output and the corresponding price.
Answer:
First, calculate the marginal revenue (MR) by taking the derivative of the total revenue (TR) with respect to Q. TR is P*Q, so:
\[ TR = (100 -。