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. $15, 250 in 11 years at 7 percent. (Do not round intermediate calculations. Round your final answer to 2 decimal places.) b. $19, 600 in 18 years at 11 percent. (Do not round intermediate calculations. Round your final answer to 2 decimal places.) c. $8,000 each year for 14 years at 8 percent. (Do not round intermediate calculations. Round your final answer to 2 decimal places.) d. $55,000 each year for 20 years at 14 percent. (Do not round intermediate calculations. Round your final answer to 2 decimal places.)