Chapter 4 The Time Value of Money 61
51. Find the present value of an income stream which has a negative flow of $100 per year for 3
years, a positive flow of $200 in the 4th year, and a positive flow of $300 per year in Years 5
through 8. The appropriate discount rate is 4 percent for each of the first 3 years and 5 percent for
each of the later years. Thus, a cash flow accruing in Year 8 should be discounted at 5 percent for
some years and 4 percent in other years. All payments occur at year-end.
52. Assume that you are graduating, that you plan to work for 4 years, and then to go to law school
for 3 years. Right now, going to law school would require $17,000 per year (for tuition, books,
living expenses, etc.), but you expect this cost to rise by 8 percent per year in all future years.
You now have $25,000 invested in an investment account which pays a simple annual rate of 9
percent, quarterly compounding, and you expect that rate of return to continue into the future.
You want to maintain the same standard of living while in law school that $17,000 per year
would currently provide. You plan to save and to make 4 equal payments (deposits) which will be
added to your account at the end of each of the next 4 years; these new deposits will earn the
same rate as your investment account currently earns. How large must each of the 4 payments be