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Math Help - Hats off to helpful mathaticians

  1. #1
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    Hats off to helpful mathaticians

    Ok so 5 people place their names in a hat, what is the probability that they will each pull out there own name?
    So correct me if i'm wrong (chances are I am) but
    there are 5! = 120 permutations, with only 1/120 chance of them chosing their own names
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  2. #2
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    Hello, TommyBoy22!

    Ok, so 5 people place their names in a hat.
    What is the probability that they will each pull out there own name?

    So correct me if i'm wrong (chances are I am) but ...

    There are 5! = 120 permutations, with only \tfrac{1}{120} chance of them chosing their own names.
    You are absolutely correct!


    Another approach:

    The first has a \tfrac{1}{5} chance of getting his name.
    The second has a \tfrac{1}{4} chance of getting his name.
    The third has a \tfrac{1}{3} chance of getting his name.
    . . . and so on.

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