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If A and B are two events associated with a random experiment such that P(A ∪ B) = 0.8, P(A ∩ B) = 0.3 and \(P(\bar A)\)= 0.5 , find P(B). |
Answer» Given A and B are two events And, P(A’) = 0.5 P(A ∩ B) = 0.3 P(A ∪ B) = 0.8 ∵ P(A’) = 1 – P(A) ⇒ P(A) = 1 – 0.5 = 0.5 We need to find P(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) ∴ P(B) = P(A ∪ B) + P(A ∩ B) – P(A) ⇒ P(B) = 0.8 + 0.3 – 0.5 = 1.1 – 0.5 = 0.6 ∴ P(B) = 0.6 |
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