On his 25th birthday, Yves deposited $4000 in a fund paying 5%/year compounded annually and continued to make such deposits each year, the last of which on his 49th birthday. Beginning on his 50th birthday, Yves plans to make equal annual withdrawals of $20 000.
a) How many such withdrawals can be made?
b) What additional sum paid with the last withdrawal will exhaust the fund?
c) What sum paid one year after the last full withdrawal will exhaust the fund?