Final answer:
The population of a country with a 6.1% annual growth rate will approximately double in 11.8 years, as calculated using the rule of 72.
Step-by-step explanation:
To calculate how long it will take for the population of a country to double with an annual growth rate of 6.1%, we can use the rule of 72. The rule is a simple way to estimate the number of years required for a quantity to double at a constant growth rate. By dividing 72 by the annual growth rate, we get an approximation of the doubling time.
Using this method, we divide 72 by 6.1, which equals approximately 11.8 years for the population to double. This rule of 72 is widely used in finance and economics, but it is also applicable in cases of exponential population growth as it simplifies the understanding of compound growth rates.