什么是平均成本（Average cost)？

If a firm enjoys economies of scale up to a certain output level, and cost then increases proportionately with output, what can you say about the shape of the long -run average cost curve？

假设一个利润最大化的垄断者的生产产出为800单位，并索取每单位40美元的价格。

(1)如果产品的需求弹性为-2,求生产最后一单位产品的边际成本。

(2)厂商边际成本上的百分比价格加成为多少？

(3)假设生产最后一单位产品的平均成本为15美元，且厂商的固定成本为2000美元。求厂商的利润。

Suppose a profit - maximizing monopolist is producing 800 units of output and is charging a price of $ 40 per unit.

a. If the elasticity of demand for the product is - 2, find the marginal cost of the last unit produced.

b. What is the firm ' s percentage markup of price over marginal cost？

c. Suppose that the average cost of the last unit produced is $ I5 and the firm' s fixed cost is $ 2000. Find the firm' s profit.

A.marginal cost ＞ average cost = $16.67

B.marginal cost ＜ average cost = $16.67

C.$16.67 = marginal cost = average cost

D.$16.67 = marginal cost ＞ average cost