If A and B are mutually exclusive events, P (A) = 0.35 and P (B) = 0.45, find
(a) P (A′)
(b) P (B′)
(c) P (A ∪ B)
(d) P (A ∩ B)
(e) P (A ∩ B′)
(f) P (A′∩ B′)
P(A) = 0.35 & P(B) = 0.45 ….. (given)
P(A ∩ B) = 0 ……. (since A & B are mutually exclusive)
Now, we know that,
P (A) + P (A’) = 1
0.35 + P (A’) = 1
P(A’) = 1 – 0.35
P (A’) = 0.65
Now, we know that,
P (B) + P (B’) = 1
0.45 + P (B’) = 1
P (B’) = 1 – 0.45
P (B’) = 0.55
Now, we know that,
P (A U B) = P(A) + P(B) – P(A ∩ B)
P (A U B) = 0.35 + 0.45 – 0
P (A U B) = 0.80
Since A & B are mutually exclusive events,
Thus, P (A ∩ B) = 0
P (A ∩ B’) = P (A) - P (A ∩ B)
= 0.35 – 0
= 0.35
P (A’ ∩ B’) = P (A U B)’
= 1 – P (A U B)
= 1 – 0.8 …… [from (c)]
= 0.2