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Math Help - Just checking

  1. #1
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    Just checking

    I have P(B|A) and P(A), there isn't a quick way to get P(B) off this is there?

    A and B are not independent.

    Thanks,

    Brendan
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  2. #2
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    Hello, Brendan!

    I have P(B|A) and P(A).

    There isn't a quick way to get P(B) off this, is there? . no

    \,A and \,B are not independent.

    From Bayes' Theorem, we have: . P(B|A) \;=\;\dfrac{P(A \cap B)}{P(A)}

    . . Hence: . P(A \cap B) \;=\;P(B|A)\cdot P(A)


    But without more information, such as P(A \cup B),

    . . we cannot isolate P(B).
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  3. #3
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    Thanks, I assumed that was the case but just wanted to be sure.
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