Obaidullah Hamzah, who recently sold his Ford Mustang, placed $15,000 in a savings account paying annual compound interest of 7 percent.

a. Calculate the amount of money that will be accrued if he leaves the money in the bank for 1, 5, and 15 years.

b. If he moves his money into an account that pays 8 percent or one that pays 10 percent, rework part (a) using these new rates.

c. What conclusions can you draw about the relationship between interest rates, time, and future sums from the calculations you have completed in this problem?