Calculate the future value of $9,000 in a. 4 years at an interest rate of 8% per year. b. 8 years at an interest rate of 8% per year. c. 4 years at an interest rate of 16% per year. d. Why is the amount of interest eamed in part a less than half the amount of interest earned in part b? a. 4 years at an interest rate of 8% per year. The future value of $9,000 in 4 years at an interest rate of 8% per year is $ (Round to the nearest dollar.)