#### Answer

3.1

#### Work Step by Step

Based on the definition of the natural logarithm, we know that $ln(x)=log_{e}x$.
Furthermore, recall that $log_{b}x=y$ is equivalent to the statement $b^{y}=x$ (where $x\gt0$, $y$ is a real number, and $b\gt0$ and $b\ne1$).
Therefore, $ln(e^{3.1})=log_{e}e^{3.1}=3.1$, because $e^{3.1}=e^{3.1}$.