What is the present value of the following series of prospective payments?
a. $600 a month for 3 years at 13% compounded annually.
b. $5,000 a year for 5 years at 16% compounded semi annually.
c. $2,500 each year for 10 years at 8% compounded quarterly.
d. $14,000 each quarter for 4 years at 12% compounded monthly.