Chapter 04 – Future Value, Present Value, and Interest Rates
a. Describe the calculation you need to make to determine how much you must save to
purchase an annuity paying $50,000 per year for the rest your life. Assume the
interest rate is 7 percent.
b. If you want to keep your purchasing power constant, how would your calculation
change if you expected inflation to average 2 percent for the rest of your life?
Answer:
b. If you want to have $50,000 in purchasing power for each year of your retirement,
you would need to calculate:
8. Most businesses replace their computers every two to three years. Assume that a computer
costs $2,000 and that it fully depreciates in 3 years, at which point it has no resale value and
is thrown away. (LO1)
a. If the interest rate for financing the equipment is equal to i, show how to compute the
minimum annual cash flow that a computer must generate to be worth the purchase.
Your answer will depend on i.
b. Suppose the computer did not fully depreciate but still had a $250 value at the time it
was replaced. Show how you would adjust the calculation given in your answer to
part (a).
c. What if financing can only be had at a 10 percent interest rate? Calculate the
minimum cash flow the computer must generate to be worth the purchase using your
answer to part (a).
Answer:
a. If x = minimum annual cash flow:
9. Some friends of yours have just had a child. Thinking ahead, and realizing the power of
compound interest, they are considering investing for their child’s college education, which
will begin in 18 years. Assume that the cost of a college education today is $125,000. Also
assume there is no inflation and no tax on interest income used to pay college tuition and
expenses. (LO2)
a. If the interest rate is 5 percent, how much money will your friends need to put into
their savings account today to have $125,000 in 18 years?
b. What if the interest rate were 10 percent?
c. The chance that the price of a college education will be the same 18 years from now
as it is today seems remote. Assuming that the price will rise 3 percent per year, and
that today’s interest rate is 8 percent, what will your friend’s investment need to be?
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