Numbers X X and Y Y between 0 and 1 are chosen randomly. The joint probability density

Numbers $X$ and $Y$ between 0 and 1 are chosen randomly. The joint probability density is $p(x,y)=1$ if $0\le x\le 1$ and $0\le y\le 1$, and $p(x,y)=0$ otherwise. Calculate the probability $P$ that the product $XY$ is at least $\frac{1}{2}$.