Given: A and B are two events.
P (A) = 0.5, P (B) = 0.3 and P (A ∩ B) = 0.2
Now we need to find P (A ∪ B).
By definition of P (A or B) under axiomatic approach (also called addition theorem) we know that:
P (A ∪ B) = P (A) + P (B) – P (A ∩ B)
So, P (A ∪ B) = P (A) + P (B) – P (A ∩ B)
P (A ∪ B) = 0.5 + 0.3 – 0.2
= 0.8 – 0.2
= 0.6
∴ P (A ∪ B) is 0.6