a. How long will it take to triple your money with an interest rate of 10 percent? b. On the advice of your broker ten years ago, you invested in a $6 stock that is now selling for $30. At what rate has your capital grown? c. Your father is about to retire. His firm has given him the option of retiring with a lump sum of $50,000 or an annuity of $8,000 for ten years. Which is worth more now, if the discount rate is (1) 6%, (2) 18%? d. You are offered a $15,000 life insurance policy requiring thirty annual payments of $195 each. What is the compound value of the payments that you will have made after the policy is paid up, assuming that the discount rate is 10 percent?