The interest rate on a $200,000 mortgage loan is 5% compounded semiannually.

a. Calculate the monthly payment for each of 15-year, 20-year, 25-year, and 30-year amortizations.

b. By what percentage must the monthly payment be increased for a 20-year amortization instead of a 25-pear amortization?

c. By what percentage must the monthly payment be increased for a 20-year amortization instead of a 30-year amortization?

d. For each of the four amortization periods in Part (a), calculate the total interest paid over the entire amortization period. Assume that the interest rate and payments do not change and the final payment equals the others.