According to the rule of 72, if Randall invests $700 and $1900 into two separate accounts with the same interest rate, which amount will double faster? A. Both will double at the same rate. B. $1900 C. $700 D. None of the above

The answer is A.) Both will double at the same rate. Now I am going to explain how I know. If the interest rate of each is 1% this means that 1% of each will be added to the accounts per month. $1900 x 1% is $19 per month. $700 x 1% is $7 per month. Now I will divide 1900 by 19 to find how many months it will take to double the money in that account. It will take 100 months for the account with $1900 in it to double. Now I will multiply $700 by $7 to get 100 months also. This means that each account will take 100 months to double so your answer is A.) Both will double at the same rate.

A: 700 im pretty sure ...

or

Divide 72 with the years of growth rate and the quotient will then be the number of years it will take your money to double.