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Homework Help: Simple statistical question

  1. Jan 28, 2006 #1
  2. jcsd
  3. Jan 28, 2006 #2


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    Well, the chance of each individually being right is 1/365 (ignoring leap years and assuming people's guesses are independent of the person's actual birthday, which is probably not true), and if they are independent then it follows the binomial distribution, so the answer is
    C(408, 13) * (1/365)^13 * (364/365)^395. Unless you're interested in the probability of at least 13 being right.
    Last edited: Jan 28, 2006
  4. Jan 28, 2006 #3
    Sorry, statistics represents a bit of a gap in my education. What is this C function, and how do I calculate it/look it up?

    Let's go with exactly 13 of them being right.
  5. Jan 28, 2006 #4
    C(n, k) = [tex]\frac{n!}{(k!)(n-k)!}[/tex]
    Last edited: Jan 28, 2006
  6. Jan 28, 2006 #5
    Thanks. 1 in 5,370,675,393 I make it.
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