What is the least number of complete years in which a sum of money at 20% compound interest will be more than doubled?
If principal amount be P, then we need to find n for the following equation
P(1 + 0.2)n > 2P
(1.2)n > 2
n(log 1.2) > n log 2 (log means log to the base e i.e natural log)
n > (log 2 / log 1.2) > 3.8
So, Complete years = 4
The correct option is A.