A sum of money at simple interest becomes 36 times itself in 100 years. In how many years will it become 57 times itself?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 160 years
Becoming \(n\) times means an interest of \(n-1\) times the sum, and at simple interest the interest grows in proportion to time.
36 times: interest \(=35\) times the sum, earned in 100 years
57 times: interest \(=56\) times the sum
\(\displaystyle \text{Time}=100\times\frac{56}{35}=160\) years
The sum becomes 57 times itself in 160 years.