A debt of $7,000 accumulated interest at 9.5% compounded quarterly for 15 months, after which the rate changed to 8.5% compounded semi-annually for the next six months. What was the total amount owed at the end of the entire 21-month period?

Compounded Quarterly

A method of calculating interest where the interest is added to the principal four times a year, resulting in the interest from one quarter earning interest in the next.

Compounded Semi-annually

Interest calculation method where the interest is added to the principal amount after every six months, increasing the total amount on which future interest accruals are based.

Interest

Money paid at a particular rate for the use of money lent, or for delaying the repayment of a debt.