Question

In how many years will a sum of money double itself at 6.1% simple interest per annum?

• A. 2 years
• B. 4 years
• C. 8 years
• D. 16 years

Hint:

To find the time in which a sum doubles at simple interest, use: \[ \text{SI} = P \Rightarrow \frac{P \times R \times T}{100} = P \Rightarrow T = \frac{100}{R} \]

Answer 1

The Correct Option is D

Use the formula for Simple Interest.
The formula for simple interest is: \[ \text{SI} = \frac{P \times R \times T}{100} \] If a sum doubles, the interest earned is equal to the principal, so: \[ \text{SI} = P \] Substitute into the formula: \[ P = \frac{P \times 6.1 \times T}{100} \] Canceling \(P\) from both sides: \[ 1 = \frac{6.1T}{100} \quad \Rightarrow \quad T = \frac{100}{6.1} \approx 16.39 \] Rounding to the nearest integer, we get: \[ T \approx 16 \text{ years} \]