DSE-2010,question 57

[sonudelhi]

57.a consumer has a utility function u(x,y)=xy suppose the consumer demands bundle (x,y).Now suppose sellers of good x offers a "buy one get  one free scheme.Given this scheme,consumer buys bundle (xd,yd) and get additional xd for free.which of the following statement must be true?
a.  xd>x and yd>y
b.  xd>x and yd=y
c.  Xd>x and yd<y
d.  xd=x and yd=y

how should i proceed?

[Chocolate Frog]

The wording is admittedly slightly muddled up, but it's really quite easy.

His consumption bundle is (2xd,yd) with the BOGOF scheme. Just solve for utility maximisation as if px had halved and py had stayed the same. You'll get xd = x and yd = y.

[sonudelhi]

thank you  so much!