Final answer:
The Rule of 72 allows you to estimate the number of years needed to double an investment or economic measure like GDP by dividing 72 by the annual growth rate or interest rate.
Step-by-step explanation:
According to the Rule of 72, you can double your money in an approximate number of years when you divide 72 by the annual interest rate or growth rate.
None of the options provided, such as doubling money in 72 years, 72 months, 72 days, or 72 hours, correctly describe the rule of 72.
Instead, the rule is used to estimate the number of years it will take to double an investment or GDP at a given annual percent growth rate or interest rate.
For example, to estimate how long it will take for countries like India, Spain, and South Africa to double their standards of living using the Rule of 72, you would divide 72 by their annual growth rates.
If the growth rate is 6%, you would calculate 72/6, which results in 12 years for the standard of living to double.
This rule provides a quick and easy way to understand the impact of growth rates on doubling times for investments or economic measures such as GDP.