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Math Help - Likelihood

  1. #1
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    Likelihood

    Hi!

    If there are 10 people in the same room and they were all born in the same year what would be the likelihood that at least two of them were born exactly the same day?

    Please help me with that one
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  2. #2
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    Quote Originally Posted by Shandy View Post
    Hi!

    If there are 10 people in the same room and they were all born in the same year what would be the likelihood that at least two of them were born exactly the same day?

    Please help me with that one
    The probability is 1 - the probability of them all being born on different days.

    p = 1 - \frac{365!}{365^{10}(365-10)!}

    p = 1 - \frac{365\times 364\times 363\times 363 \ldots 356}{365^{10}}

    p \approx 0.1169481777
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  3. #3
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    Quote Originally Posted by Shandy View Post
    Hi!

    If there are 10 people in the same room and they were all born in the same year what would be the likelihood that at least two of them were born exactly the same day?

    Please help me with that one
    Read this: Birthday problem - Wikipedia, the free encyclopedia
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  4. #4
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    Quote Originally Posted by mr fantastic View Post
    If I recall correctly, there is also a nice discussion of the problem in the short Arthur C Clarke novel A Fall of Moondust.
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