Answer
3
Work Step by Step
The product rule holds that $\sqrt[n] a\times\sqrt[n] b=\sqrt[n] (ab)$ (where $\sqrt[n] a$ and $\sqrt[n] b$ are real numbers).
Therefore, $\sqrt[4] 27\times\sqrt[4] 3=\sqrt[4] (27\times3)=\sqrt [4] 81=3$
We know this because $3^{4}=81$.