Question

Population of a town is 176400. If it increases at the rate of 5% per annum, what will be its population 2 years hence ? What was the population 2 years ago?

Answer 1

$$\begin{gathered} \mathrm{Present}\mathrm{population}=176400 \\ \mathrm{r}=5\% \\ \mathrm{t}=2\mathrm{year} \\ \mathrm{SI}=\frac{\mathrm{prt}}{100}=\frac{176400\times 5\times 2}{100}=17640 \\ \mathrm{So}\mathrm{after}\mathrm{two}\mathrm{year}\mathrm{the}\mathrm{population}\mathrm{will}\mathrm{be}=176400+17640=194040 \\ \mathrm{Now}\mathrm{let}\mathrm{the}\mathrm{population}\mathrm{was}\mathrm{x}\mathrm{before}\mathrm{two}\mathrm{year}\mathrm{So}, \\ \mathrm{SI}=\frac{\mathrm{x}\times 5\times 2}{100}=\frac{\mathrm{x}}{10} \\ \mathrm{x}+\frac{\mathrm{x}}{10}=176400 \\ 11\mathrm{x}=1764000 \\ \mathrm{x}=160363.6~160364 \end{gathered}$$