Probability: Independent Events

Question

Let A and B be independent events with P(A) = .4 and P(B) = .2. Find P(A ∪ B).

Answer 1

P(A) = 0.4 and P(B)= 0.2. Use the Addition Rule.

P(A ∪ B) = P(A) + P(B) - P(A ∩ B) = 0.4 + 0.2 - (0.4)(0.2) = 0.4 + 0.2 - 0.08 = 0.6 - 0.08 = 0.52

The probability of A or B is 0.52.

Answer 2

P(A and B) = P(A) * P(B) = 0.4 * 0.2 = 0.08