Sally’s parents deposited $15,000 into a college savings account on her third birthday. the account had an interest rate of 9.6% compounded annually. they were hoping that the money would double twice by the time she was 18 years old. using the rule of 72, mc009-1.jpg will their hopes come true? yes, the $15,000 will double each 7.5 years. in 15 years, it will double twice. yes, the $15,000 will double in 7.5 years and be four times as much in 15 years. no, the $15,000 will only double once in 15 years, not double twice. no, it will take 30 years for the $15,000 to double twice.