With work explained. You want to know in which scenario you need to save the LEAST amount of money monthly. First plan is to have $1,250,000 in 25 years when you retire and your investments will earn 9%. The second option is to receive a monthly payment of $6,000 in retirement (your retirement will last 25 years) and you will earn a 4% rate of return on your investments in retirement. You have already saved $40,000 in one investment that will earn 7%, and $20,000 in a money market account that will earn 1.5%.