Rate to triple in twelve years

Statement

A fund promises to triple the capital in $12$ years with annual compounding. What annual rate is implied?

Solution

From $C\,(1+i)^{12} = 3C$ it follows $(1+i)^{12} = 3$. $1+i = 3^{1/12} \ \Rightarrow\ i = 3^{1/12} - 1 \approx 1{.}09587 - 1 = \boxed{9{.}59\%}.$