Let $T=W / \sqrt{V / r}$, where the independent variables $W$ and $V$ are, respectively, normal with mean zero and variance 1 and chi-square with $r$ degrees of freedom. Show that $T^{2}$ has an $F$ -distribution with parameters $r_{1}=1$ and $r_{2}=r$. Hint: What is the distribution of the numerator of $T^{2} ?$