7. With some services, e.g., checking accounts, phone service, or pay TV, a consumer is offered a choice
of two or more payment plans. One can either pay a high entry fee and get a low price per unit of
service or pay a low entry fee and a high price per unit of service. Suppose you have an income of
$100. There are two plans. Plan A has an entry fee of $20 with a price of $2 per unit. Plan B has an
entry fee of $40 with a price of $1 per unit for using the service. Let x be expenditure on other goods
and y be consumption of the service.
a. Write down the budget equation that you would have after you paid the entry fee for each of the two
plans.
b. If your utility function is xy, how much y would you choose in each case?
c. Which plan would you prefer? Explain.
8. Marie’s utility function is U(x, y) = min3x + 2y, 2x + 5y, where x is the number of units of sugar she
consumes and y is the number of units of spice she consumes. She is currently consuming 12 units of
sugar and 40 units of spice and she is spending all of her income.
a. Draw a graph showing her indifference curve through this point.
b. The price of spice is $1. In order for this to be her consumption bundle, what must the price of sugar
be and what must her income be?
9. Murphy’s utility function is U(x, y) = min4x + y, 2x + 2y, x + 4y. Murphy is consuming 12 units of x
and 6 units of y.
a. Draw the indifference curve through this point. At what points does this indifference curve have
kinks?
b. The price of good x is $1. What is the highest possible price for y? What is the lowest possible price
for y?