Question

The simple interest on a certain sum for $8$ months at $4\%$ simple interest is Rs $129$ less than the simple interest on the same sum for $15$ months at $5\%$ per annum. Then the sum is

• A. $Rs.3,400$
• B. $Rs.3,500$
• C. $Rs.3,600$
• D. $Rs.3,700$

Answer 1

The correct option is C $Rs.3,600$

Let the sum be$=x$
As per problem,
$\Rightarrow \frac{x\times 5\times 15}{100\times 12}-\frac{x\times 4\times 8}{100\times 12}=129$

$\Rightarrow \frac{75x-32x}{1200}=129$

$\Rightarrow 43x=154800$,
$x=\frac{154800}{43}=3600$
The sum is $Rs.3600$