Al has a 25-year $250,000 mortgage with a 12% nominal interest rate convertible monthly.

Immediately after the 120^th payment, he refinances the mortgage.

The interest rate is reduced to 9% nominal convertible monthly for the remaining term of the loan.

Determine the average rate of interest rate earned by the bank over the entire term of the loan, expressed as a nominal rate convertible monthly.

Possible answers are: 10.5 or 11.6 or 10.8 or 10.2 or 11.4 percent. Thanks!