Given two independent events A and B such that P(A) = 0.3, P(B) = 0.6.
Find
(i) P(A and B) (ii) P(A and not B)
(iii) P(A or B) (iv) P(neither A nor B)
Given: P(A) = 0.3, P(B) = 0.6.
(i) P(A and B)
As A and B are independent events.
⇒ P(A and B) = P (A ∩ B) = P(A) . P(B)
= 0.3 × 0.6
= 0.18
(ii) P(A and not B)
⇒ P(A and not B) = P (A ∩ B’) = P(A) - P(A ∩ B)
= 0.3 - 0.18
= 0.12
(iii) P(A or B)
⇒ P(A or B) = P(A ∪ B)
As we know, P (A ∪ B) = P(A) + P(B) - P (A ∩ B)
⇒ P (A ∪ B) = 0.3 + 0.6 – 0.18
⇒ P (A ∪ B) = 0.72
(iv) P(neither A nor B)
P(neither A nor B) = P(A’ ∩ B’)
As, { A’ ∩ B’ =(A ∪ B)’}
⇒ P(neither A nor B) = P ((A ∪ B)’)
= 1 - P (A ∪ B)
= 1 - 0.72
= 0.28