Question

The population of a town increases by $10\%$ annually. If the present population is $22000$, find its population a year ago.

Answer 1

Given: Present population $=22000$
Population of a town increases by $10\%$ annually

Let the population of the town a year ago be ${}^{\prime }{x}^{\prime }$

$\Rightarrow$ Present population $=x+10\%$ of $x$

$\Rightarrow x+10\%$ of $x=22000$

$\Rightarrow x+\frac{10}{100}\times x=22000$

$\Rightarrow x+\frac{x}{10}=22000$

$\Rightarrow \frac{11x}{10}=22000$

$\Rightarrow x=\frac{10\times 22000}{11}$

$\Rightarrow x=20000$

Hence, population of the town a year ago was $20000$.