SSC CHSL 15 Nov 2015 Shift 2 Paper

Principal added after each year = Rs.x
Rate of interest = 5% and time period = 3 years
Simple interest after 1 year = $\frac{\mathit{P}\times \mathit{R}\times \mathit{T}}{100}$
= $\frac{\mathit{x}\times 5\times 1}{100}=\mathit{R}\mathit{s}.\frac{\mathit{x}}{20}$
Principal for 2nd year = $\left(2\mathit{x}+\frac{\mathit{x}}{20}\right)=\mathit{R}\mathit{s}.\frac{41\mathit{x}}{20}$
S.I. after 2nd year= $\frac{41\mathit{x}}{20}\times \frac{5}{100}$
= Rs. $\frac{41\mathit{x}}{400}$
Principal for 3rd year = $\left(3\mathit{x}+\frac{41\mathit{x}}{400}\right)=\mathit{R}\mathit{s}.\frac{1241\mathit{x}}{400}$
S.I. after 3rd year = $\left(3\mathit{x}+\frac{1241\mathit{x}}{8000}\right)=\mathit{R}\mathit{s}.\frac{25241\mathit{x}}{8000}$