4. Suppose you invest $5,000 per year for three years at an interest rate of 7.25%. After year 3, you make no new investments, but leave your money invested. How much money will you have in 15 years?

5. You receive $100 from your grandmother. Ally Bank will guarantee a 1% annual interest rate indefinitely. How long will it take to quintuple your money? (That is, you have 5 times more money).

7. Suppose you charge me a 9% annual interest rate and I promise to pay you $3,000 a year for four years (first payment is one year from today) plus $9,000 five years from now. How much is this stream of cash flows worth today?