The company you work for will deposit $600 at the end of each month into your retirement fund. Interest is compounded monthly. You plan to retire 30 years from now and estimate that you will need $5,000 per month out of the account for 25 years. If you believe you can earn 6% compounded monthly while you're working and 4% after you retire, how much do you need to contribute to the account monthly, in addition to your company deposit, in order to meet your objective?