Question: Suppose that X, Y have joint PDF

\[{{f}_{X,Y}}\left( x,y \right)=\left\{ \begin{aligned} & 8xy\,\,\,\,\,\,0\le x\le y\le 1 \\ & 0\text{ elsewhere} \\ \end{aligned} \right.\]

(a) Find var(XY) and (b) correlation coefficient ρ(X, XY).