A certain amount will become six times in 20 years. How long does it take for the same amount to become 5 times? Assume the same rate of simple interest in each case.
Answer & explanation
Correct answer: option 4
let principle = Rs100
100 becomes 600 in 20 years
So Interest = 600-100=Rs 500
Now 100 becomes 500 (5 times)
∴ Interest = Rs 400
Interest becomes \(\frac{4}{5}\) times
Then time also becomes \(\frac{4}{5}\) times
∴ \(\frac{20×4}{5}\) = 16 years