SSC CHSL 15 Nov 2015 Shift 1 Paper

Let principal amount = Rs.x and rate of interest = 18%
Compound interest when compounded annually = $\mathit{P}{\left(1+\frac{\mathit{R}}{100}\right)}^{\mathit{T}}$
= $\mathit{x}{\left(1+\frac{18}{200}\right)}^4={\left(\frac{109}{100}\right)}^4\mathit{x}$
= Rs. 1.41158161$\mathit{x}$
According to ques, ⇒ $\left(1.41158161\mathit{x}-1.3924\mathit{x}\right)=960$
⇒ $0.01918161\mathit{x}=960$
⇒ $\mathit{x}=\frac{960}{0.01918161}\approx 50047.93$
∴ Sum of money given = Rs. 50,000