In its first 10 years a mutual fund produced an average annual return of 21.55%. Assume that money invested in this fundcontinues to earn 21.55% compounded annually. How long will it take money invested in this fund to double?
Compound interest formula:
$\displaystyle A=P(1+i)^n$
P is the principal (initial amount invested)
A is the final amount ...... here A=2*P....(the money invested in this fund doubles)
i = 0.2155
You need to find n.
Hint: It will involve logarithms.
See how you go!