The present population of a country estimated to be 10 crores is expected to increase to 13.31 crores during… · ABC26GN2438

10 crores $\times\left(1+\frac{\mathrm{R}}{100}\right)^{3}=13.31$ crores. $$\therefore\left(1+\frac{\mathrm{R}}{100}\right)^{3}=\frac{13.31 \text { crores }}{10 \text { crores }}=\frac{13.31}{10}=\frac{1331}{1000}=\left(\frac{11}{10}\right)^{3} .$$ So, $$\begin{aligned} \left(1+\frac{R}{100}\right) & =\frac{11}{10} \Leftrightarrow\left(1+\frac{R}{100}\right) \\ & =\left(1+\frac{1}{10}\right) \Leftrightarrow \frac{R}{100}=\frac{1}{10} \Leftrightarrow R=10 . \end{aligned}$$