The population of a town is 64000. If the annual birth rate is 11.7% and the annual death rate is 4.2%, calculate the population of the town after 3 years.

Given,

P = 64000

Net growth rate (R) = Birth rate - Death rate

= 11.7% - 4.2% = 7.5%

n = 3 years

By formula,

Population after n years = $P \times \Big(1 + \dfrac{r}{100}\Big)^n$

Substituting the values in formula,

$\text{Population after 3 years} = 64000 \times \Big(1 + \dfrac{7.5}{100}\Big)^3 \\[1em] = 64000 \times \Big(\dfrac{100 + 7.5}{100}\Big)^3 \\[1em] = 64000 \times \Big(\dfrac{107.5}{100}\Big)^3 \\[1em] = 64000 \times \Big(\dfrac{43}{40}\Big)^3 \\[1em] = 64000 \times \dfrac{79507}{64000} \\[1em] = 79507$

Hence, the population of the town after 3 years = 79,507.