Correct Answer - Option 4 : 400%
Given
Amount = 25 principal
Time = 6 years
Formula used
If amount becomes 'x' times of Principal in y years, then rate of interest is calculated as follows:
r = [100(x - 1)/y]%
Calculation
R = [100(25 - 1)/6]%
⇒ [100 × 24/6]%
⇒ 400%
∴ The rate of interest is 400%.
