Gustav decided that he wants to retire in 25 years, and he wants to have enough saved to provide him a monthly income of $3,000 for 30 years. To date, he has no savings. He believes that he can earn 6% on his investments before and after retirement. How much does he need to save monthly to reach his retirement goal? He makes the deposits at the end of the month. His retirement income will begin at the end of the first month.

a. $863

b. $583

c. $722

d. $789