Question 1023095: I have no idea how to find P(AuB) if A and B are dependent. Also do not know how to find P(B/A), again if A and B are dependent the instructor gave me this info to go along with the question: P(A):0.61, P(B):0.13 and P(A/B):0.44
Please help I am completely lost when it comes to this. Thanks
Answer by robertb(5830)   (Show Source):
You can put this solution on YOUR website! P(AuB) = P(A) + P(B) - P(A&B), where & stands for intersection.
We have to find P(A&B). From conditional probability, P(A|B) = P(A&B)/P(B)
==> P(A&B) = P(A|B)P(B) = 0.44*0.13 = 0.0572
==> P(AuB) = P(A) + P(B) - P(A&B) = 0.61 + 0.13 - 0.0572 = 0.6828.
BTW, from Bayes' Theorem, P(A|B)P(B) = P(B|A)P(A), so it now gets easy to find P(B|A).
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