Answer:
11.6 years
Explanation:
When we are trying to determine how long will it take an investment to double using compound interest, the simplest way is to use the rule of 72. But the problem is that it doesn't work very well with odd numbers.
So we have to use math:
FV = PV (1 + r)ⁿ
PV = X and FV = 3X
3X = X(1 + 10%)ⁿ
3 = (1 + 0.1)ⁿ
log 3 = log 1.1ⁿ
log 3 = n x log 1.1
n = log 1.1 / log 3
n = 11.6 years
