Question

A sum of money doubles in 4 years under compound interest at certain rate of interest

Answer 1

Answer:

18%

Explanation:

Thumb rule is that money doubles in 72/x years where x is the approx. interest rate compounding annually. In your question 72/x is 4 years so x would be 18% approx.

Say if you have to compute interest rate if money double in 6 years then answer will be 72/6 = 12 % approx.