If the population of a town is 64000 and its annual increase is 10%, then its population at the end of 3 years will be :

Answer: Option B

Present population = 64000
1^st year = 66400
2^nd year = 6400 + 640
3^rd year = 6400 + 2 × 640 + 64

Total population after 3 years
= 64000 + 3 × 6400 + 3 × 640 + 64
= 85184

Alternate:
Population after n years
$$\begin{array}{rl}& \Rightarrow {\text{p}}^{\prime }=\text{p}{\left(1\pm \frac{\text{R}}{100}\right)}^{\pm \text{n}}\\ & {\text{p}}^{\prime }=64000{\left(1\pm \frac{10}{100}\right)}^3\\ & =85184\end{array}$$