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Homework Help: Conditional Probability (ii)

  1. Dec 16, 2009 #1
    box A contains 2 red balls,
    box B contains 2 white balls,
    box C contains 1 red ball and 1 white ball,

    A box is selected at random (with equal probabilities) and one ball is taken at random from that box.

    (i) Compute the probability of selecting a white ball using Bayes Rule.

    A(1/3) _____ Red(1/6)
    .........|____ Red(1/6)

    B(1/3)______White(1/6)
    ........|_____White(1/6)

    C(1/3)______Red(1/6)
    ........|_____White(1/6)

    so.. P(White) = [(1/3)*(1/6)] + [(1/3)*(1/6)] + [(1/3)*(1/6)]
    = 1/6

    Correct?


    (ii)Compute the conditional probability that B has been selected given that the ball is white.

    P(B|White) = P(B intersect White) / P(White)

    what is my P(B intersect White)?
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
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