SSC CHSL 7 Mar 2018 Shift 2 Paper

Let principal amount = Rs.$100\mathit{x}$
⇒ Simple interest = $\frac{20}{100}\times 100\mathit{x}=\mathit{R}\mathit{s}.20\mathit{x}$
Let rate of interest = $\mathit{r}\%$ and time period = 5 years
⇒ Simple interest = $\frac{\mathit{P}\times \mathit{R}\times \mathit{T}}{100}$
⇒ $\frac{100\mathit{x}\times \mathit{r}\times 5}{100}=20\mathit{x}$
⇒ $\mathit{r}=\frac{20}{5}=4\%$
Let the interest will be equal to the principal in = $\mathit{t}$ years at 4% rate
⇒ $\frac{100\mathit{x}\times 4\times \mathit{t}}{100}=100\mathit{x}$
⇒ $\mathit{t}=\frac{100}{4}=25$ years