经济学的题目 求解答过程

Question

Suppose the government imposes a binding price ceiling on the price of milk that results in a shortage of milk in the market. The market for milk is perfectly competitive. In which of the following case would the shortage associated with the price ceiling be the largest?

a) The own-price elasticity of both the demand and supply of milk is small.
b) The own-price elasticity of both the demand and supply of milk is large.
c) The own-price elasticity of the supply of milk is large and the own-price elasticity of the demand for milk is small.
d) The own-price elasticity of the demand for milk is large and the own-price elasticity of the supply of milk is small.
e) None of the above. The binding price ceiling would result in a surplus and not a shortage.

给的答案是b，为什么是b啊？

Answer 1

Case 1: Baseline

上图是我们考虑的Baseline Case。横坐标Quantity，纵坐标Price，S是供给函数，D是需求函数。在没有price ceiling的情况下，图中的P^N是市场出清价格（market clearing price）。题目中说price ceiling是binding的，所以可得P^C低于P^N，如图中蓝色横线所示。在这种情况下，shortage是quantity demanded与quantity supplied的差，即图中横坐标上的红色竖线所表示的部分。

我们现在考虑更改供给和需求函数的斜率之后，shortage会如何变化。首先考虑把两个函数变陡峭的情况（注意：市场出清价格P^N保持不变）。

Case 2: Steeper Curves

如上图所示，这种情况下，shortage变小了。

接下来考虑函数较baseline case更平缓的情况：

Case 3: Flatter Curves

如上图所示，这种情况下，shortage更大了。

因此：需求和供给函数越平缓，则shortage越大，反之则越小。当两个函数无限平缓的时候，shortage就无限大。而函数越趋平缓，随着price的变化，quantity的变化就越大，也就是说own-price elasticity越大。因此正确答案是B）。

Answer 2

经济学的题目求解答过程，正在关注不知道。