Answer:
1. The most you would be willing to pay for having a freshly washed car before going out on a
date is $6. The smallest amount for which you would be willing to wash someone else's car is
$3.50. You are going out this evening, and your car is dirty. How much economic surplus
would you receive from washing it?
The economic surplus from washing your dirty car is the benefit you receive from doing so ($6)
minus your cost of doing the job ($3.50), or $2.50.
2. To earn extra money in the summer, you grow tomatoes and sell them at the farmers' market
for 30 cents per pound. By adding compost to your garden, you can increase your yield as
shown in the table below. If compost costs 50 cents per pound and your goal is to make as much
money as possible, how many pounds of compost should you add?
Pounds
of
compost
Pounds
of
tomatoes
Marginal
Cost
($)
Marginal
Benefit
(pounds)
Marginal
Benefit
($)
Net
Benefits
Marginal
Net
Benefits
0 100 ---- 0 --- 0 ---
1 120 0.50 20 6.00 5.50 5.50
2 125 0.50 5 1.50 6.50 1.00
3 128 0.50 3 0.90 6.90 0.40
4 130 0.50 2 0.60 7.00 0.10
5 131 0.50 1 0.30 6.80 - 0.20
6 131.5 0.50 0.5 0.15 6.45 - 0.35
The benefit of adding a pound of compost is the extra revenue you’ll get from the extra tomatoes
that result. The cost of adding a pound of compost is 50 cents. By adding the fourth pound of
compost you’ll get 2 extra pounds of tomatoes, or 60 cents in extra revenue, which more than
covers the 50-cent cost of the extra pound of compost. But adding the fifth pound of compost
gives only 1 extra pound of tomatoes, so the corresponding revenue increase (30 cents) is less than
the cost of the compost. You should add 4 pounds of compost and no more.
3. Residents of your city are charged a fixed weekly fee of $6 for garbage collection. They are
allowed to put out as many cans as they wish. The average household disposes of three cans of
garbage per week under this plan. Now suppose that your city changes to a "tag" system. Each
can of refuse to be collected must have a tag affixed to it. The tags cost $2 each and are not
reusable. What effect do you think the introduction of the tag system will have on the total
quantity of garbage collected in your city? Explain briefly.
In the first case, the cost is $6/week no matter how many cans you put out, so the cost of
disposing of an extra can of garbage is $0. Under the tag system, the cost of putting out an extra
can is $2, regardless of the number of the cans. Since the relevant costs are higher under the tag
system, we would expect this system to reduce the number of cans collected.
Explanation:
