My spouse and I are each 62 and hope to retire in three years. After retirement we will receive $7,500 per month after taxes from our employers' pension plans and $1,500 per month after taxes from Social Sec urity. Unfortunately, our monthly living expenses are $15,000. Our social obligations preclude further economies.

We have $1,000,000 invested in a high-grade, tax-free municipal-bond mutual fund. The return on the fund is 3.5% per year. We plan to make annual withdrawals from the mutual fund to cover the difference between our pension and Social Security income and our living expenses. How many years before we run out of money?