Question

please say the answer it's urgent​

Answer 1

given P(A') = 2/3 (probability of not happening A)

so, P(A) = 1 - P(A')

= 1 - 2/3

= 1/3

now, we know that

n(A u B) = n(A) + n(B) - n(A n B)

dividing by n(S) i.e. sample space we have

P(A u B) = P(A) + P(B) - P(A n B)

If A and B are mutually exclusive event

P(A n B) = 0

P(A u B = P(A) + P(B)

3/4 = 1/3 + P(B)

P(B) = 3/4 - 1/3

= (9 - 4)/12

= 5/12