NO.PZ2018062003000025
问题如下:
We observe the demand function for food is given by the equation
Qdpf =80−3Ppf+0.1I+0.5Ppd
Qdpf is the number of food, Ppf is the price of food, I is the income , Ppd is the price of drink)
We know that:Ppf= 30, I=110, and Ppd= 20.
The income elasticity of demand for food will be:
选项:
A.
0.4.
B.
0.6.
C.
1.
解释:
C is correct.
From the above function, we get:
ΔQdpf/ I= 0.1
Qdpf = 80−3∗30+0.1∗110+0.5∗20=11
When I = 110, the income elasticity will be (0.1)(110/11)=1
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,先求出需求量,即:
Qdpf = 80−3∗30+0.1∗110+0.5∗20=11
之后我们再利用需求收入弹性公式求解,即,
Qdpf = 80−3∗30+0.1∗110+0.5∗20=11
(Δdpr/ΔI)(I/Qdpr)=(0.1)(110/11)=1
(Δdpr/ΔI)(I/Qdpr) 这个公式怎么来的?麻烦把每一个量,帮忙解释一下。感谢