If $\overrightarrow P = 3\widehat i + \sqrt 3 \widehat j + 2\widehat k$ and $\overrightarrow Q = 4\widehat i + \sqrt 3 \widehat j + 2.5\widehat k$ then, the unit vector in the direction of $\overrightarrow P \times \overrightarrow Q $ is ${1 \over x}\left( {\sqrt 3 \widehat i + \widehat j - 2\sqrt 3 \widehat k} \right)$. The value of $x$ is _________.