顯示性偏好 - 經濟

學校:中山大學

教師:吳教授

科目:個經

題目:Sally consumes housing(denote the number of units of housing by b) and
other goods(a composite good whose units are measured by y), both of
which she likes.

Initially she has an income of $100, and the price of a unit of housing
is $10. At her initial basket she consumes 2 units of housing. Later her
income rises to $120; unfortunately, the price of housing also rises to
$15, and the price of composite good does not change.

At her later basket she consumes 1 unit of housing. Using revealed
preference analysis(without drawing indifference curve), what can you
say about how she ranks her initial and later basket?


我的想法:如下

initial basket: 買2個housing,1個$10;所以100-20=80
先假設買y個composite,剩下的80元全部買composite,
則1個composite要80/y元.


later basket : 買1個housing,1個$15;所以120-15=105
一樣將105全部買composite,(composite價格不變)
則共買了105y/80 個composite.


我用initial basket價格乘上initial basket數量以及later basket數量做比較:
10(2)+80/y(y)=100 小於 10(1)+80/y(105y/80)=115

later basket價格乘上initial basket數量以及later basket數量做比較:
15(2)+80/y(y)=110 小於 15(1)+80/y(105y/80)=120


由上述式子可以看出不論在什麼樣的價格之下,皆是later basket較優.
不知我這樣的想法和答案有沒有哪裡是錯誤的,請板上高手指教謝謝.

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