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Homework Help: Probability of 3rd drawing is red?

  1. Sep 25, 2011 #1
    There are 7 balls in box--red and white.
    What is probability of p-th drawing is red?

    Condition:return of previous drawing and not
    returning of previous drawing.

    Please help me these two conditions please
    Thanks in advance
    Last edited: Sep 25, 2011
  2. jcsd
  3. Sep 25, 2011 #2


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    Science Advisor

    You are the same person who did the "10 boys and girls in line"?

    The same thing happens here- if x of the seven balls is red and the drawing of samples is "with replacement", then the probability any one draw is red is x/7. If the drawing is "without replacement" then the probability depends on the previous history. The "a-priori" probability without that information is still x/7.
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