Answer:
a. If she begins saving today; How much money will she have when she is 65?
Assuming that the student started saving the day of her birthday, she will have $1,825 at the end of each year. So we must find the future value of an ordinary annuity with 45 payments worth $1,825 and 9% interest rate:
FV = $1,825 x 525.85873 (FV annuity factor, 9%, 45 periods) = $959,692.18
b. If she did not start saving until she was 45 years old, how much would she have at 65?
FV = $1,825 x 51.16012 (FV annuity factor, 9%, 20 periods) = $93,367.22
c. How much must the 45-year-old deposit monthly to catch the 20-year old?
$959,692.18 = annuity payment x 51.16012
annuity payment = $959,692.18 / 51.16012 = $18,758.60