Consider the savings plans for two investors — we’ll call them Mary and Bill—who began investing 10 years apart. Both put the same amount of money aside ($100 per month for 20 years for a total of $24,000). Mary and Bill earned the same interest rate, which was 8% compounded monthly. Mary started her investment at age 35, and Bill started his investment at age 45. By the age of 65, how much greater than Bill’s plan was Mary’s plan?

(a) 122%

(b) 48%

(c) 89%

(d) 55%

(e) It is not greater