3. (4 pts) On their 2016 birthday, twins Bill and Bob decide they would like to retire when they are 60. Bill immediately puts $400 at the end of each month into an account paying 8% compounded monthly, but becomes disabled in a skiing accident and stops making payments after his 40th birthday. From then on his money only cams interest. Bob, on the other hand, decides to enjoy life until his 40 birthday when he starts putting away $800 (twice as much!) at the end of each month into an account paying 8% compounded monthly. Compute the accumulated value of their accounts on their 60 birthday, and decide who has the most money for retirement a.) Accumulated value of Bill's account b.) Accumulated value of Bob's account