For a certain period, simple interest on ₹1000 at 10% per annum is ₹100 more than that on ₹800. Find the period (in years).
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 5
Simple interest is \(\displaystyle\frac{P\times R\times T}{100}\). At the same rate and for the same period, it is proportional to the principal, so the difference between the two interests is the interest on the difference of the principals.
Difference of the principals \(=1000-800=200\) rupees
Interest on 200 rupees for 1 year at 10% \(\displaystyle =\frac{200\times10\times1}{100}=20\) rupees
The difference of the interests is 100 rupees, so the period \(=100\div20=\) 5 years