Answer
${\frac{1}{4}}$
Work Step by Step
A natural logarithm is a logarithm to base $e$. As shown on page 582, when a natural logarithm is written in the form $ln (x)$, this is equivalent to the expression $log_{e}x$.
Therefore, $ln \sqrt[4]e=ln (e^{\frac{1}{4}})=log_{e}e^{\frac{1}{4}}=\frac{1}{4}$. We know this, because $(e)^{\frac{1}{4}}=e^{\frac{1}{4}}$.
