18. Mr. Doody, at age 70, is expected to live for 15 years. If he can invest at 12% per annum compounded monthly, how much does he need now to guarantee himself $300 every month for the next 15 years? 19. Daryl wishes to save money to provide for his retirement. Beginning one month from now, he will deposit a fixed amount into a retirement savings account that will earn 12% p.a. compounded monthly for 30 years. Then, one year after making his final deposit, he will withdraw $100,000 annually for 25 years. How much should Daryl deposit for the first 30 years to meet his objective if the fund earns the interest rate of 12.68% p.a., compounded annually during the last 25 years? 20. The Happy Hang Glide Company is purchasing a building and has obtained a $190,000 mortgage loan for 20 years. The loan bears a compound interest rate of 17% p.a. and calls for equal annual installment payments at the end of each of 20 years. What is the amount of annual payment? 21. A home buyer is purchasing a $140,000 house. The down payment will be 20% of the price of the house, and the remainder will be financed by a 30-year mortgage at a rate of 9.8% interest compounded monthly. What will the monthly payment be? Compare the monthly payments and the total amounts of interest paid if a 15-year mortgage is chosen instead of a 30-year mortgage