The present population of a town is 15625. If the population increases at the rate of 4% every year, what will be the increase in the population in next 3 years?

By formula,

V = $V_0\Big(1 + \dfrac{r}{100}\Big)^n$

Putting values in formula we get,

$V = 15625\Big(1 + \dfrac{4}{100}\Big)^3 \\[1em] = 15625 \times \Big(\dfrac{104}{100}\Big)^3 \\[1em] = 15625 \times \Big(\dfrac{26}{25}\Big)^3 \\[1em] = 15625 \times \dfrac{26}{25} \times \dfrac{26}{25} \times \dfrac{26}{25} \\[1em] = \dfrac{15625 \times 17576}{15625} \\[1em] = 17576.$

Increase in population = 17576 - 15625 = 1951.

Hence, the increase in population in next 3 years = 1951.