#### Answer

please see details in "work step by step"

#### Work Step by Step

Exponential growth model: $A=A_{0}e^{kt} \qquad(k>0)$
($A_{0}$ is the initial quantity, $A$ is the quantity after time t).
We solve for t (the time it takes for $A$ to become 3$A_{0}$).
$3A_{0}=A_{0}e^{k\mathrm{r}}\displaystyle \qquad .../\times\frac{1}{A_{o}}$
$3=e^{k\mathrm{r}}\qquad .../$ take ln( ) of both sides
$\mathrm{l}\mathrm{n}3 =kt$
$t=\displaystyle \frac{\ln 3}{k}$
The population will triple in $t=\displaystyle \frac{\ln 3}{k}$ years,
which confirms the problem statement.