(a) An electron has becn obscrved to have its spin in the direction of the z-axis of a rectangular coordinate system. What is the probability that a second observation will show the spin to be directed in - z plane at an ugle 0 with respect to the z-axis? (b) The total spin of the neutron and proton in a deuteron is a triplet state. The resultant spin has been observed to be parallel to the z-axis of a rectangular coordinate system. What is the probability that a second observation will show the proton spin to be parallel to the z-axis?

(a) An electron has becn obscrved to have its spin in the direction of the z-axis of a rectangular coordinate system. What is the probability that a second observation will show the spin to be directed in - z plane at an ugle 0 with respect to the z-axis? (b) The total spin of the neutron and proton in a deuteron is a triplet state. The resultant spin has been observed to be parallel to the z-axis of a rectangular coordinate system. What is the probability that a second observation will show the proton spin to be parallel to the z-axis?