You put $20,000 on deposit on your 30th birthday at 5% compounded annually. On your 40th birthday, the account begins earning 6%. Then on your 50th birthday, it begins earning 7%. You plan to withdraw equal annual amounts on your 61st, 62nd, . . . , 70th birthdays.
a. How much will be your annual withdrawal?
b. On your 65th birthday, you decide to withdraw the entire amount remaining. How much do you withdraw?