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何珊 · 2021年11月20日

课件上写的是 数量比收入

NO.PZ2016010802000025

问题如下:

The market demand function for four-year private universities is given by the equation

Qdpr ​=84−3.1Ppr​+0.8I+0.9Ppu​

where Q pr d is the number of applicants to private universities per year in thousands, P pr is the average price of private universities (in thousands of USD), I is the household monthly income (in thousands of USD), and P pu is the average price of public (government-supported) universities (in thousands of USD). Assume that Ppr is equal to 38, I is equal to 100, and P pu is equal to 18.

The income elasticity of demand for private universities is closest to:

选项:

A.

0.5.

B.

0.8.

C.

1.3.

解释:

C is correct.

From the demand function:

Solve for Qdpr :
∆Q /∆Idpr = 0.8 (coefcient in front of the income variable)
Qdpr = 84 – 3.1Ppr + 0.8I + 0.9Ppu
= 84 – 3.1(38) + 0.8(100) + 0.9(18)
= 62.4

At I = 100, the income elasticity of demand

(ΔQdpr​/ΔI)(I​/Qdpr​)​=(0.8)(100/62.4)=1.3

考点:需求收入弹性

解析:题目给出了需求函数的表达式,带入数字,先求的私立大学的需求量,即:

Qdpr = 84 – 3.1Ppr + 0.8I + 0.9Ppu
= 84 – 3.1(38) + 0.8(100) + 0.9(18)
= 62.4

之后我们再利用需求收入弹性公式求解,即,

(ΔQdpr​/ΔI)(I​/Qdpr​)​=(0.8)(100/62.4)=1.3

课件上写的是数量比收入~为什么解析是收入比数量?
1 个答案

笛子_品职助教 · 2021年11月21日

嗨,努力学习的PZer你好:


(ΔQdpr​/ΔI)(I​/Qdpr​)​=(0.8)(100/62.4)=1.3

课件上写的是数量比收入~为什么解析是收入比数量?


收入弹性,就是收入变动,对需求量变动的影响,是数量比收入,收入一定在分母。


解析这里,把除法变成乘法了,除法变乘法,分子分母就颠倒了。看上去的变形式是收入比数量。其实还是数量比收入。

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虽然现在很辛苦,但努力过的感觉真的很好,加油!