Answer
$11.612 \%
Work Step by Step
Recall:
$A = P \left(1+\dfrac{r}{n} \right)^{n t}$
$P:$ The principal amount
$r:$ Annual interest rate
$n:$ Number of compoundings per year
$t:$ Number of years
$A:$ Amount after $t$ years
Here we have:
$t= 10$
$\text{Compounded annually } \to n = 1$
Since the investment is to be tripled $ \hspace{20pt} \therefore A = 3P$
$3P = P\left(1+\dfrac{r}{1} \right)^{1 \times 10}$
$3P = P (1+r)^{10}$
Divide both sides by $P$:
$3 = (1+r)^{10}$
$(1+r) = \sqrt[10]{3}$
$r = \sqrt[10]{3}-1$
$r \approx 0.11612$
$r = \boxed{11.612 \%}$
