Question

The population of a town was 280000 two years ago. If it increased

by 7% & 5% respectively in the last two years, then the present

population is ?

Answer 1

Answer :

314580

Explanation :

Two years ago, population of the town was

• 2,80,000

Two years hence, the population decreases by 7% in first year and 5% in second year.

Find the present population.

Present population is given by :

${ \underline{ \boxed{ \sf \longrightarrow \: p{ \bigg( 1 + \dfrac{r_1}{100} \bigg) \bigg(1 + \dfrac{r_2}{100} \bigg)}}}} \\ \sf \: where \: \\ \bullet \sf \: p \: is \: the \:population \\ \sf\bullet \: r_1 and \: r_2\: are \: the \: respective \: rates \\ {\underline{ \sf{on \: substituting \: the \: values : }}} \\ \sf \longrightarrow \: 280000\bigg(1 + \frac{7}{100} \bigg)\bigg(1 + \frac{5}{100} \bigg) \\ \\ \sf \longrightarrow \: 280000\bigg( \frac{107}{100} \bigg)\bigg( \frac{105}{100} \bigg) \\ \\ \sf \longrightarrow \: 28 \times 107 \times 105 \\ \\ \sf \longrightarrow \: 314580$

∴ Present population : 314580