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Homework Help: Find the probability it will be red

  1. Oct 1, 2005 #1
    I need a help with this question please:

    Urn 1 contains 5 red balls & 3 black balls.
    Urn 2 contains 3 red balls & 1 black ball.
    Urn 3 contains 4 red balls & 2 black balls.
    If an urn is selected at random and a ball is drawn, find the probability it will be red.

    Thanks for helping.
     
  2. jcsd
  3. Oct 2, 2005 #2
    If the urn is selected at random, can't you just treated as if all the balls were in 1 huge urn? I think it's just 12/18 right?
     
  4. Oct 2, 2005 #3
    no, probability of getting each urn is 1/3

    so

    (1/3)(5/8)+(1/3)(3/4)+(1/3)(4/6)=49/72

    I am thinking this way, but am not sre.
     
  5. Oct 2, 2005 #4
    sounds right.
     
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