Question

The difference between compound interest and simple interest on a certain sum at $10\%$ per annum for $2$ years is Rs. $631$. Find the sum.

• A. Rs. $56000$
• B. Rs. $63100$
• C. Rs. $50000$
• D. Rs. $60000$

Answer 1

The correct option is B Rs. $63100$

Let the sum be $x$.
C.I.$=\left[\begin{array}{c}x{\left\{\begin{array}{c}1+\left(\begin{array}{c}\frac{10}{100}\end{array}\right)\end{array}\right\}}^2-x\end{array}\right]=\frac{21x}{100}$

S.I.$=\frac{x\times 10\times 2}{100}$
$\Rightarrow$C.I -S.I $=\frac{x}{100}$
$\Rightarrow \frac{x}{100}=631$
$\Rightarrow x=63100$