9. You Invest $7500/year into a 401K earning 6 %/year Interest. a) How much is your 401K worth after 40 years? b) You are getting close to retiring and you want to collect $40,000/year for 30 years. If you 401 K is now earning 3% a year, then how much do you need in your 401K to fund the yearly payments of $40,000 a year.