Question:
The present population of a town is 25000. It grows at 4%, 5% and 8% during first year, second year and third year respectively. Find its population after 3 years.
Solution:
Here,
$\mathrm{P}=$ Initial population $=25,000$
$\mathrm{R}_{1}=4 \%$
$\mathrm{R}_{2}=5 \%$
$\mathrm{R}_{3}=8 \%$
$\mathrm{n}=$ Number of years $=3$
$\therefore$ Population after three years $=\mathrm{P}\left(1+\frac{\mathrm{R}_{1}}{100}\right)\left(1+\frac{\mathrm{R}_{2}}{100}\right)\left(1+\frac{\mathrm{R}_{3}}{100}\right)$
$=25,000\left(1+\frac{4}{100}\right)\left(1+\frac{5}{100}\right)\left(1+\frac{8}{100}\right)$
$=25,000(1.04)(1.05)(1.08)$
$=29,484$
Hence, the population after three years will be 29,484 .