Question

The population of a city is 20,000. If the rate of increase is 25% every year, then find the population of the city after 2 years.

Answer 1

$\text{Given: Population, P}=20,000\text{Rate of increase in population,}R=25\%\text{and}\text{Number of years, n}=2$ years

$\text{Let population after 2 years be A.}$
$\left[1mark\right]$

$A=P\times {[1+\frac{R}{100}]}^n=20000\times [1+\frac{25}{100}{]}^2=20000\times [1+\frac{1}{4}{]}^2=20000\times [\frac{5}{4}{]}^2=20000\times \frac{25}{16}=31250$

$\therefore \text{The population after 2 years}=31,250.$
$\left[1mark\right]$