According to this formula, about how long will it take a population to double if the annunal growth rate is 3.2%? Note:

Question

The formula below gives T, the approximate time in years it takes a population to double if the annunal growth rate is R percent.

 

T= 70

      R

Answer 1

Hello, thank you for taking the time to post your question!

You just want to plug in R = 3.2 into the formula that was given! So that means taking

T = 70 / R = 70 / 3.2 = 21.875

Rounding up to the nearest year that would be 22 years

I hope that helps get you moving in the right direction! Feel free to reach out if you have any additional questions beyond that :)

Answer 2

Hi Kristany,

 

Using the formula, we would have

 

   T = 70 / 3.2, or 21.875 years

 

I'd say the approximate value is 22 years, rounding to the nearest whole year.

 

For the math behind the "rule of 70", please see

 

   http://www.ecofuture.org/pop/facts/exponential70.html

 

Note that instead of the "rule of 70" some people use the "rule of 72", for example

 

   http://en.wikipedia.org/wiki/Rule_of_72

 

Either way, we get the same approximate value of 22 years (when rounded to the nearest whole year).

 

Best wishes.