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Homework Help: Statisitics - Random Variables

  1. Mar 4, 2012 #1
    1. The problem statement, all variables and given/known data

    There is a population of 30 elk. 6 elk are captured, tagged and then released into the wild. Then later 5 elk are captured, what is the probability that k elk are tagged?

    2. Relevant equations

    p=6/30 = 1/5

    P = [itex]\stackrel{n}{k}[/itex] * pk * (1-p)k

    [itex]\stackrel{n}{k}[/itex] is n choose k

    3. The attempt at a solution

    plug in the values.

    but the big question I have is: Is this a binomial RV?
  2. jcsd
  3. Mar 4, 2012 #2
    I think this would be hypergeometric.
  4. Mar 4, 2012 #3
    to elaborate, the way you have it, as a binomial, would mean that each deer caught has a 6/30 chance of being tagged. but this is not the case. if you catch a deer and it is tagged, then there are 24 untagged deer and 5 tagged deer remaining. so on your next catch, you would a 5/29 chance of catching a tagged deer. but you can use a hypergeometric distribution on this to make it a little easier.
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