A box containing two spin-one gyros $\mathrm{A}$ and $\mathrm{B}$ is found to have angular-momentum quantum numbers $j=2, m=1$. Determine the probabilities that when $J_{z}$ is measured for gyro $\mathrm{A}$, the values $m=\pm 1$ and 0 will be obtained.
What is the value of the Clebsch-Gordan coefficient $C(2,1 ; 1,1,1,0)$ ?