How much would you have to invest today to receive the following? Use Appendix B or Appendix D for an approximate answer, but calculate your final answer using the formula and financial calculator methods.

a. $16,800 in 10 years at 15 percent. (Do not round intermediate calculations. Round your final answer to 2 decimal places.)

b. $21,000 in 15 years at 12 percent. (Do not round intermediate calculations. Round your final answer to 2 decimal places.)

c. $8,800 each year for 20 years at 13 percent. (Do not round intermediate calculations. Round your final answer to 2 decimal places.)

d. $60,000 each year for 50 years at 9 percent. (Do not round intermediate calculations. Round your final answer to 2 decimal places.)