Rs 1500 is invested in two parts. The first part earns interest at 6% per annum and the second part at 5% per annum. If the total interest at the end of one year is Rs 85, find the sum invested at 5%.
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Rs 500
If the whole Rs 1500 earned 6%, the interest would be more than Rs 85; each rupee moved to 5% lowers the interest by 1 paisa.
Interest if all were at 6% \(=6\%\) of 1500 \(=\) Rs 90
Shortfall \(=90-85=\) Rs 5
Each rupee at 5% earns 1% less, that is Rs 0.01 less
Sum at 5% \(\displaystyle =\frac{5}{0.01}=\) Rs 500
The sum invested at 5% is Rs 500.