2014年 春季学期 经济学原理2 期中1 清华

经济学原理II（2014年春季学期）

期中考试1（A卷答案）

（2014/4/2）

注意：请将所有题目的答案写在答题册上，写在本试题纸上一律无效。本试卷满分为50分。

I.选择一个正确的答案（每小题4分，共12分）

I.1．Suppose more college students major in engineering and computer science. Consider its effect on the market for labor in the computer manufacturing industry. For any given quantity of employment, the marginal product of labor will ; in equilibrium the marginal product of labor will .

A.not change; decrease

B.decrease; decrease

C.increase; increase

D.not change; increase or decrease (cannot decide)

I.2．活力社区中的一半的居民在一年中的奇数月份挣到1.5万元，在偶数月份挣到0.5万元，另一半居民在奇数月份挣到0.5万元，在偶数月份挣到1.5万元。安稳社区中的一半居民在一年的每个月中总是挣到1万，另一半居民每个月总是挣到0.5万。从单独一个月来看，社区的收入差距更小。从一整年的总收入来看，社区的收入差距更小。总体上看社区更合意。

A.活力；活力；活力

B.安稳；活力；活力

C.安稳；安稳；安稳

D.活力；安稳；活力

I.3．Many years ago, Peggy paid $500 to put together a new record collection. Today, she sold her albums at a garage sale for $100. How do all her actions mentioned above affect current GDP? GDP many years ago?

A.Her actions will increase GDP many year ago by $500 but not affect current GDP.

B.Her actions will increase GDP many year ago by $500 and increase current GDP by $100.

C.Her actions will affect neither current GDP nor GDP many years ago.

D.Her actions will increase current GDP by $100 but not affect GDP many years ago.

II.判断正误并说明理由（5分）。

收入法GDP（即从收入角度衡量的GDP）和支出法GDP（即从支出角度衡量的GDP）可以不相等。因为家庭的支出可以大于或者小于收入。

错误。单独从一个家庭来说，其支出可以大于或者小于收入。但这里的支出法GDP包括了消费、投资、政府购买和净出口，不仅仅指家庭的消费。这里的收入法GDP也可能不仅仅是家庭的收入，还包括企业未分配利润。收入法GDP和支出法GDP必定相等，是因为：第一，支出法GDP必定等于产品法GDP，出于市场等价交换原则；第二；产品法GDP必定等于收入法GDP，出于企业获取的增加值必定分配完毕（包括留利在内）的核算原则。最终收入法GDP和支出法GDP必定相等。

III. Labor Market and Goods Market (11 pts)

Suppose a freeze destroys part of the Florida orange crop.

a. Explain what happens to the price of oranges and the marginal product of orange pickers as

the result of the freeze. (2 pts)

The price of oranges will (generally) go up, because in the orange market supply decreases. The marginal product of orange pickers will go down, because the other input (oranges on the trees) becomes scarier.

b. Suppose the demand for oranges is perfectly elastic . What happens to the equilibrium wage

and quantity of orange pickers? Use graphs for both orange market and orange picker market to explain you answers. (4 pts)

See the graph below. Since the demand for oranges is perfectly elastic, the price of orange would not change. And since the MPL of orange pickers goes down, the VMPL of/demand for orange pickers will go down. As a result, the equilibrium wage and quantity of orange pickers will go down.

c. Suppose the demand for oranges is perfectly inelastic . What happens to the equilibrium

wage and quantity of orange pickers? Use graphs for both orange market and orange picker market to explain you answers. (4 pts)

See the graph below. Since the demand for oranges is perfectly inelastic, the price of orange would go up but the equilibrium quantity of orange would not change. Since the MPL of orange pickers goes down, then in equilibrium the quantity of orange pickers must go up to keep the quantity of orange in equilibrium at the same level. This in turn requires that the demand for orange pickers will go up. Thus the equilibrium wage and quantity of orange pickers will go up. In other words, the price of oranges goes up so much that it dominates the effect of decreasing MPL and finally make the VMPL go up.

d. In general, can you say the freeze is a good news or bad news for orange pickers? (1 pt) No. It can increase or decrease the demand for orange pickers, thus benefit or hurt them.

P

Q L Q1 Q2 P1=P2 w1

w2

L1 L2