Jeffrey invested money in a mutual fund for seven years. The interest rate on the mutual fund was 5% compounded quarterly for the first three years and 3% compounded semi-annually for the next four years. At the end of the seven years, Jeffrey's mutual fund had accumulated to $35,198.50.

a. Calculate the amount that was in the mutual fund after the first three years when the interest rate changed.

Round to the nearest cent

b. Calculate the amount that was invested in the mutual fund at the beginning of the period.

Round to the nearest cent

c. Calculate the total amount of interest earned from this investment.