(Compound annuity) What is the accumulated sum of each of the following streams of payments? a. $500 a year for 10 years compounded annually at 9 percent b. $108 a year for 6 years compounded annually at 9 percent c. $31 a year for 12 years compounded annually at 12 percent d. $23 a year for 4 years compounded annually at 5 percent a. What is the accumulated sum of $500 a year for 10 years compounded annually at 9 percent? (Round to the nearest cent) b. What is the accumulated sum of $108 a year for 6 years compounded annually at 9 percent? (Round to the nearest cent) c. What is the accumulated sum of $31 a year for 12 years compounded annually at 12 percent? (Round to the nearest cent) d. What is the accumulated sum of $23 a year for 4 years compounded annually at 5 percent? (Round to the nearest cent)