What is the accumulated sum of each of the following streams of payments?
a. $ 500 a year for 10 years compounded annually at 5 percent
b. $ 100 a year for 5 years compounded annually at 10 percent
c. $ 35 a year for 7 years compounded annually at 7 percent
d. $ 25 a year for 3 years compounded annually at 2 percent