What is the present value of $4,000 received a. 14 years from today when the interest rate is 8% per year? b. 28 years from today when the interest rate is 16% per year? c. 7 years from today when the interest rate is 4% per year? Your brother has offered to give you either $84,000 today or $140,000 in 11 years. If the interest rate is 8% per year, which option is preferable? Suppose you invest $750 in an account paying 7% interest per year. a. What is the balance in the account after 4 years? How much of this balance corresponds to "interest on interest"? b. What is the balance in the account after 31 years? How much of this balance corresponds to "interest on interest