Explanation:
That is, the event A ∪ B will occur if either A or B occurs. In Example 4.1(a), if A = {g} is the event that the child is a girl and B = {b} is the event that it is a boy, then A ∪ B = {g, b}.
Associative law: (E ∪ F)∪G = E ∪ (F ∪ G)
Distributive law: (E∪F)G=EG∪FG
Commutative law: E ∪ F = F ∪ E