21. A loan of 20,000 is being paid by installments of 1000 at the end of each six month period and a final smaller payment made half a year after the last regular payment. The interest rate for the loan is a nominal interest rate of 6% convertible semi-annually. a. Find the outstanding loan balance when the borrower has made payments equal to 90% of the original amount of the loan. b. Find the number of payments needed for the borrower to pay off his/her debt. c. Find the amount of the final payment. d. Find the total interest paid throughout the duration of the loan period