A and B are two events such that P(A) = 0.54, P(B) = 0.69 and P(A ∩ B) =0.35. Find (i) P(A ∪ B), (ii) (iii)
(iv)
Given A and B are two events
And, P(A) = 0.54 P(B) = 0.69 P(A ∩ B) = 0.35
By definition of P(A or B) under axiomatic approach we know that:
P(A ∪ B) = P(A) + P(B) – P(A ∩ B)
We have to find-
i) P(A ∪ B) = P(A) + P(B) – P(A ∩ B)
= 0.54 + 0.69 – 0.35 = 0.88
ii) P(A’ ∩ B’) = P(A ∪ B)’ {using De Morgan’s Law}
⇒ P(A’ ∩ B’) = 1 – P(A ∪ B) = 1 – 0.88 = 0.12
iii) P(A ∩ B’) = This indicates only the part which is common with A and not B ⇒ This indicates only A.
P(only A) = P(A) – P(A ∩ B)
∴ P(A ∩ B’) = P(A) - P(A ∩ B) = 0.54 – 0.35 = 0.19
iv) P(A’ ∩ B) = This indicates only the part which is common with B and not A ⇒ This indicates only B.
P(only B) = P(B) – P(A ∩ B)
∴ P(A’ ∩ B) = P(B) – P(A ∩ B) = 0.69 – 0.35 = 0.34