In what time will the simple interest on ₹2200 at 6% per annum be the same as that on ₹1650 at 9% per annum in 10 years?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 11 years and 3 months
1. Calculate Simple Interest for the Second Case
The formula for Simple Interest ($SI$) is:
$SI = \frac{P \times R \times T}{100}$
For the second case:
- Principal ($P_2$) = ₹1650
- Rate ($R_2$) = 9% per annum
- Time ($T_2$) = 10 years
$SI_2 = \frac{1650 \times 9 \times 10}{100} = 165 \times 9 = ₹1485$
2. Calculate the Time for the First Case
We are told that the interest for the first case ($SI_1$) is the same as the second case ($SI_2 = ₹1485$).
For the first case:
- Principal ($P_1$) = ₹2200
- Rate ($R_1$) = 6% per annum
- Interest ($SI_1$) = ₹1485
- Time ($T_1$) = ?
Using the formula rearranged for Time:
$T = \frac{SI \times 100}{P \times R}$
$T_1 = \frac{1485 \times 100}{2200 \times 6}$
$T_1 = \frac{1485}{22 \times 6} = \frac{1485}{132}$
$T_1 = 11.25 \text{ years}$
3. Convert Decimal Years to Months
- $11.25 \text{ years} = 11 \text{ years} + 0.25 \text{ years}$
- $0.25 \times 12 \text{ months} = 3 \text{ months}$
Final Answer:
The time taken will be 11 years and 3 months.