NAME 157
(a) Assume for simplicity of calculations that the house and the insulation
will last forever. Calculate the present value of the dollars saved on fuel
from each of the three options if the interest rate is 10%. The present
(b) Each plan requires an expenditure of money to undertake. The differ-
ence between the present value and the present cost of each plan is: Plan
(c) If the price of fuel is expected to remain constant, which option should
he choose if he can borrow and lend at an annual interest rate of 10%?
A.
(d) Which option should he choose if he can borrow and lend at an annual
(e) Suppose that the government offers to pay half of the cost of any
insulation or solar heating device. Which option would he now choose at
(f) Suppose that there is no government subsidy but that fuel prices are
expected to rise by 5% per year. What is the present value of fuel savings
from each of the three proposals if interest rates are 10%? (Hint: If
a stream of income is growing at x% and being discounted at y%, its
present value should be the same as that of a constant stream of income
11.11 (1) Have you ever wondered if a college education is financially
worthwhile? The U.S. Census Bureau collects data on income and educa-
tion that throws some light on this question. A recent census publication
(Current Population Reports, Series P-70, No. 11) reports the average an-
nual wage income in 1984 of persons aged 35–44 by the level of schooling
achieved. The average wage income of high school graduates was $13,000
per year. The average wage income of persons with bachelor’s degrees
was $24,000 per year. The average wage income of persons with master’s
degrees was $28,000 per year. The average wage income of persons with
Ph.D.’s was $40,000 per year. These income differences probably over-
state the return to education itself, because it is likely that those people
who get more education tend to be more able than those who get less.