A positive integer from one to six is to be chosen by casting a die. Thus the elements c of the sample space C are 1, 2, 3, 4, 5, 6. Suppose C₁ = {1, 2, 3, 4} and C₂ = {3, 4, 5, 6}. If the probability set function P assigns a probability of 1/6 to each of the elements of C, compute P(C₁), P(C₂), P(C₁ ∩ C₂), and P(C₁ ∪ C₂).