5. A small coffee company roasts coffee beans in its shop. The unroasted beans cost the company $2 per
pound. The marginal cost of roasting coffee beans is $(150 − 10q + q2)/100 per pound when q pounds
are roasted. The smell of roasting beans imposes costs on the company’s neighbors. The total amount
that neighbors would be willing to pay to have the shop stop roasting altogether is 5q2, where q is the
number of pounds being roasted. The company sells its output in a competitive market at $4.50 per
pound. What is the socially efficient amount of coffee for the company to roast?
the square root of 10 pounds.
6. Nadia Comaneci and Mr. X have preferences defined over pizza, p, and trampolines, t. They have
identical utility functions, U(p, t) = p + 2,000t1/2. Each pizza costs $1 and each trampoline costs
$1,000. Nadia and Mr. X like to share, and indeed trampolines are a public good for them. Pizza,
however, is a private good. We don’t know their exact incomes, but we do know that each of them
earns at least $10,000.
The Pareto efficient number of trampolines for them is 4.
The Pareto efficient number of trampolines for them is 1.
The Pareto efficient number of trampolines for them cannot be determined without
knowing how the costs will be shared.
The Pareto efficient number of trampolines for them is 2.
Since their preferences are homothetic, their income elasticity of demand for pizza is −1.
7. Just north of the town of Muskrat, Ontario, is the town of Brass Monkey, population 6,400. Brass
Monkey, like Muskrat, has a single public good, the town skating rink, and a single private good,
Labatt Ale. Everyone’s utility function is Ui (Xi, Y) = Xi − 81/Y, where Xi is the number of bottles of ale
consumed by i and Y is the size of the skating rink in square meters. The price of ale is $1 per bottle.
The cost of the skating rink to the city is $4 per square meter. Everyone has an income of at least
$5,000. What is the Pareto efficient size for the town skating rink?
8. Bob and Ray are thinking of buying a sofa. Bob’s utility function is UB (S, MB) = (1 + S )MB and Ray’s
utility function is UR (S, MR) = (3 + S )MR, where S = 0 if they don’t get the sofa and S = 1 if they do
and where MB and MR are the amounts of money they have respectively to spend on their private
consumptions. Bob has a total of $1,200 to spend on the sofa and other stuff. Ray has a total of $1,600
to spend on the sofa and other stuff. The maximum amount that they could pay for the sofa and still
arrange to both be better off than without it is