A mortgage balance of $25,000 is to be repaid over a 10-year term by equal monthly payments at 3.5% compounded semi-annually. At the request of the mortgagor, the monthly payments were set at $425.

(a) How many payments will the mortgagor have to make?

(b) What is the size of the last payment?

(c) Determine the difference between the total amount required to amortize the mortgage with the contractual monthly payments rounded to the nearest cent and the total actual amount paid.