Question

Filmore has invested $10,000 in an account to help pay for his grandson’s education. He expects the account to return 4.5% annually. Use the rule of 72 to estimate how long it will take the $10,000 to double in value.

Answer 1

16 years

Explanation:

The rule of 72 says you can estimate the doubling time in years by dividing 72 by the interest rate in percent.

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For an interest rate of 4.5%, the rule of 72 says the doubling time is ...

72/4.5 = 16 . . . years

It will take about 16 years for the investment to double in value.