Sam is currently 30 years of age. He owns his own business, and wants to retire at the age of 60. He has little confidence in the current Social Security system. He wants to retire with an annual income of $72,000 a year. a. If Sam believes he will live to age 90, how much does he have to accumulate by the time he reaches age 60 to receive $72,000 at the end of each year for rest of his life? Sam believes he can earn 8 percent on his money in a stock mutual fund. b How much does Sam have to accumulate if he wants the payment of $72,000 at the beginning of each year