Given that n(A) = 20, n(B) = 30, n(A n B) = 8 and n(S) 100 determine P(A/B).

Question

Really need help with this question, would really appreciate a fast answer as I have a test coming up real soon and it would help a lot. thank you! 

Answer 1

Use conditional probability formula.

P(A/B) = P(A&B)/P(B).

 

P(A&B) = n(AnB)/n(S) = 8/100.

P(B) = n(B)/n(S) = 30/100

 

P(A/B) = (8/100)/(30/100)

           =8/30 = 4/15.