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Math Help - probability (drawing balls from a bag)

  1. #1
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    probability (drawing balls from a bag)

    In a bag there are 4 balls.
    2 balls are drawn together at random and both are found to be white . what is the probability that all the balls in the bag were white in color.
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  2. #2
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    Quote Originally Posted by sudhanshu View Post
    In a bag there are 4 balls.
    2 balls are drawn together at random and both are found to be white . what is the probability that all the balls in the bag were white in color.
    Here is the answer and you can figure out where all the bits and pieces come from and what assumptions have been made:

    \frac{ \frac{1}{3} \cdot \frac{{4 \choose 2}}{{4 \choose 2}} }{\frac{1}{3} \cdot \frac{{2 \choose 2}}{{4 \choose 2}} + \frac{1}{3} \cdot \frac{{3 \choose 2}}{{4 \choose 2}} + \frac{1}{3} \cdot \frac{{4 \choose 2}}{{4 \choose 2}} }
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  3. #3
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    thanx a lot ...mr. fantastic
    Last edited by sudhanshu; March 22nd 2010 at 05:36 AM. Reason: type error
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