1. An individual retires with $L in her pension fund. This money is in an account that pays i percent interest compounded m times a year. She withdraws $P each month from the fund for her expenses. Derive the expression that gives the balance of the fund after t years.
2. In problem #51, assume L = 500,000, i = 4 %, m = 12, and P = 4,200. Find the balance of the pension fund after 8 years. How long will the fund last?