Starting on the day Kenneth was born, his mother has invested $40 at the beginning of every month in a savings account that earns 3.90% compounded monthly.

a. How much did Kenneth have in this account on his 20th birthday? Assume that there was no deposit on that day.

Round to the nearest cent

b. What was his mother's total investment?

Round to the nearest cent

c. How much interest did the investment earn?

Round to the nearest cent