What is P(A'+B)

Question

If P(A)= 0.2, P(B)= 0.5 and P(AxB)= 0.1 

 

Find P(A'+B) 

Answer 1

P(A' + B) = P(A') + P(B) - P(A'xB)

 

P(A') = 1 - P(A) = 1 - .2 = .8.

 

P(A) = P(AS) = P(Ax(B+B')) = P(AxB) + P(AxB')

0.5 =                                 = 0.1 + P(AxB')

P(AxB') = 0.5 - 0.1 = 0.4

 

Then,

P(A + B') = 0.8 +0.3 - 0.4 =0.7