A sum is invested at simple interest at \(x\%\) per annum for \(3\frac{1}{2}\) years. Had it been invested at \((x+4)\%\) per annum at simple interest, it would have earned Rs 4452 more as interest. Find the sum.
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Rs 31800
The extra interest comes only from the extra 4% per annum, earned on the same sum for the same \(3\frac{1}{2}\) years.
\(\displaystyle \frac{P\times4\times3.5}{100}=4452\)
\(0.14P=4452\)
\(\displaystyle P=\frac{4452}{0.14}=31800\)
The sum is Rs 31800.