12. Problem 5.24 (Present Value for Various Discounting Periods) Find the present value of $500 due in the future under each of these conditions: a. 15% nominal rate, semiannual compounding, discounted back 8 years. Do not round intermediate calculations. Round your answer to the nearest cent. $ b. 15% nominal rate, quarterly compounding, discounted back 8 years. Do not round intermediate calculations. Round your answer to the nearest cent. $ c. 15% nominal rate, monthly compounding, discounted back 1 year. Do not round intermediate calculations. Round your answer to the nearest cent. $ d. Why do the differences in the PVs occur