A certain sum on simple interest becomes Rs 49,600 in 3 years and Rs 56,000 in 5 years. If the rate of interest has been 2% more, then in how many years would the sum have doubled?
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e.10
Difference between the sum in 3 years and 5 years = 56000 - 49600 = Rs 6400
Interest accrued in 1 year 6400/2 = Rs 3200
Interest in 3 years = Rs 9600
So, the principal = 49600 - 9600 = Rs 40000
And Rate of interest = 3200 × (100/40000) = 8%
If the rate had been 10%, then interest in 1 year = (10/100) × 40000 = Rs 4000
To double the Principal amount, we have to accrue an interest of Rs 40000 which will take 10 years with Rs 4000 per year as interest