A $116,000 mortgage loan has a 20-year amortization. a. Calculate the monthly payment at interest rates of 7.2%,9.2%, and 11.2% compounded semiannually. (Do not round intermediate calculations and round your final answers to 2 decimal places.) b. By what'percentage does the monthly payment on the 11.2% mortgage exceed the monthly payment on the 7.2% mortgage? (Do not round Intermediate calculations and round your final answer to 2 decimal places.) Percent difference c. Calculate the total interest paid over the entire 20-year amortization period at each of the three interest rates. (Assume the final payment equals the others) (Do not round intermediate calculations and round your final answers to the nearest whole dollar amount.)