知识点：Computing MPL and VMPL

例题：

Question: Computing MPL and VMPL

P = $5/bushel.  Find MPL and VMPL, fill them in the blank spaces of the table.

Then graph a curve with VMPL on the vertical axis, L on horizontal axis.

解析：

Farmer Jack’s production function exhibits diminishing marginal product: 

MPL falls as L increases. This property is very common.

Farmer Jack’s VMPL curve is downward sloping due to diminishing marginal product.

下面我们为大家准备了一道同类型的题目，请大家一起来试试解答。

Question: Changes in labour-market equilibrium

In each of the following scenarios, use a diagram of the market for (domestic) auto workers to find the effects on their wage and employment.

A.    Baby Boomers who worked in the auto industry retire.

B.    Car buyers’ preferences shift toward imported autos. 

C.    Technological progress boosts productivity in the auto manufacturing industry.

（答案见下方）

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答案解析：

A: The retirement of Baby Boomer auto workers shifts supply leftward. W rises, L falls.

B: A fall in the demand for U.S. autos reduces P. At each L, VMPL falls. Labour demand curve shifts down. W and L both fall.

C: At each L, MPL rises due to tech. progress. VMPL rises and labour demand curve shifts upward. W and L increase.