(Compound annuity) What is the accumulated sum of each of the following streams of payments? a. $500 a year for 9 years compounded annually at 11 percent. b. $104 a year for 8 years compounded annually at 8 percent. c. $34 a year for 11 years compounded annually at 13 percent. d. $27 a year for 6 years compounded annually at 6 percent