A $100,000 mortgage at 6.8% compounded semiannually with a 30-year amortization requires monthly payments. The mortgage allows

Question:

A $100,000 mortgage at 6.8% compounded semiannually with a 30-year amortization requires monthly payments. The mortgage allows the borrower to “double up” on a payment once each year. How much will the amortization period be shortened if the borrower doubles the eighth payment?