If I have e.g. P(A|B) is 0.9 and P(not A|not B) = 0.9 then how do I find P(A|not b) and P(not A|B)? Also, how do I find the P(A)?
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Originally Posted by joop If I have e.g. P(A|B) is 0.9 and P(not A|not B) = 0.9 then how do I find P(A|not b) and P(not A|B)? Also, how do I find the P(A)? Draw a tree diagram. The first two branches are B and B'. Then from each of these branches you have the two branches A and A'. It should then be clear that Pr(A | B') = 0.1 and Pr(A' | B) = 0.1. There's not enough information to calculate a numerical value of Pr(A).
I solved for P(A) by drawing a diagram (P(B) was given to us). Thanks a lot though.
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