Question

An amount doubles itself on simple interest in 4 years at a certain rate. How much time will it take for the same amount to become 4 times itself on simple interest at the same rate ?
1. 8 years
2. 10 years
3. 16 years
4. 12 years

Answer 1

Correct Answer - Option 4 : 12 years

Given:

Amount = 2 × Principal, when time = 4 years

Concept used:

Amount = P + PRT/100

P → principal R → rate of interest T → time

Calculation:

2P = P + 4PR/100

⇒ P = 4PR/100 

⇒ R = 25

Amount = 4P = P + P × 25 × T/100

⇒ 3P = PT/4

⇒ T = 12 

∴ In 12 years the amount will become 4 times itself.