A proton in a magnetic field has two spin states one aligned

A proton in a magnetic field has two spin states one aligned with B and the other anti-aligned.The energies of these spin states are E down=hyB/2 and E up=-hyB/2 where y=26.8*10^7 (Telsa sec)^-1. What are the probabilities p up and p down of observing the proton in its up and down states? write your answer in terms of y B temperature T and fundamental constants.