Schmidt works out that he would need $4,000 a month during his retired years. He is currently 25 years old and plans to work until his is 65. He assumes that he would need to make withdraws for 30 years past his retirement and that he's in a 25% tax bracket. Assuming he finds an account that will offer him a 6.25% annual interest rate compounded monthly...

a) how much should he have in his account at retirement?

b) how much should he deposit monthly during his working years to ensure he meets his goal?