Question

You have invested $1,000 in an account that promises APY of 3 percent per year. Assuming you leave the original investment and all earned interest in the account, and ignoring taxes, how long will it take to double your money?

Answer 1

Answer: The answer is 24 years.

Explanation: For this exercise we can use the rule of 72, this rule is by which investors can estimate how many years it will take for an initial investment to double. If you know the rate of return, you can know the time needed and if you know the time, you can calculate approximately the rate of return.

RULE OF 72 = APY% x NUMBER OF YEARS = 72

If we apply the formula it results =

3 × n = 72

n =
`(72)/(3)`

n = 24.