Serena wants to retire in 25 years. To plan for her retirement, she deposits $250 at the end of each month into an RRSP. After her last contribution she converts the RRSP into an RRIF from which she wants to make monthly withdrawals, at the beginning of each month, for 20 years. The interest rate is 6% compounded annually, before and after retirement, calculate the size of her retirement withdrawal. Hint: First calculate how much she will have saved when she retires.