What is the future worth of each given series of payments?
a) $6,000 at the end of each year for six years at 6% compounded annually.
b) $15,000 at the end of each year for 25 years at 8% compounded annually.
c) $8,000 at the end of each year for nine years at 7.25% compounded annually.
d) $3,000 at the end of each year for 10 years at 9.75% compounded annually.