Question

The difference between the S.I. and C.I. on a certain sum of money for 2 years at 4% per annum is Rs 20. Find the sum.

Answer 1

$$\begin{gathered} \mathrm{Given}: \\ \mathrm{CI}-\mathrm{SI}=\mathrm{Rs}20 \\ \left[\mathrm{P}{\left(1+\frac{4}{100}\right)}^2-\mathrm{P}\right]-\frac{\mathrm{P}\times 4\times 2}{100}=20 \\ \mathrm{P}\left[\left(1.{04}^2-1\right)\right]-0.08\mathrm{P}=20 \\ 0.0816\mathrm{P}-0.08\mathrm{P}=20 \\ 0.0016\mathrm{P}=20 \\ \mathrm{P}=\frac{20}{0.0016} \\ =12,500 \\ \mathrm{Thus},\mathrm{the}\mathrm{required}\mathrm{sum}\mathrm{is}\mathrm{Rs}12,500. \end{gathered}$$