Problem 13 An industrial bank will loan you $20,500 for three years to buy miscellaneous equipment for your firm. The loan must be repaid in equal monthly payments. The annual interest rate on the loan is 8.5% of the unpaid balance. How large are the monthly payments? Problem 15 You plan on buying yourself a retirement cabin in the Rocky Mountains 40 years from now. At an interest rate of 5 percent per year, how much must you invest each year (equal annual amounts beginning next year) to have $150,000 in your cabin fund in 40 years? Problem 17 15 years from now, your 2-year old son will be attending Harvard. You have determined he will need $85,000 per year for tuition and living expenses. In 15 years, you will give him a lump sum payment for the entire amount he will need, assuming that he will be able to invest the money not yet needed at 4.5% interest. You have found an investment opportunity that will yield an annual return of 6.5% on your monthly payments. How much will you have to invest each month to give your son the money he needs for his education (assume his first year at Harvard is Year 0, and his final year is Year 3)