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Math Help - ??

  1. #1
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    ??

    is this a permutation of combination?

    from a committee of fifteen members, president, vice president, and treasure are elected. In how many ways can this be accomplished?

    would i just do: 15!/(15-3)!

    or this: 15!/(15-3)!3!

    or neither? & something else...



    any thoughts or help would be great!
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  2. #2
    Rhymes with Orange Chris L T521's Avatar
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    Quote Originally Posted by sevenlovesyou View Post
    is this a permutation of combination?

    from a committee of fifteen members, president, vice president, and treasure are elected. In how many ways can this be accomplished?

    would i just do: 15!/(15-3)!

    or this: 15!/(15-3)!3!

    or neither? & something else...



    any thoughts or help would be great!
    Note that _nC_r=\frac{n!}{r!(n-r)!}.

    So what you want is _{15}C_3=\frac{15!}{3!(12!)}

    --Chris
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  3. #3
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    Quote Originally Posted by Chris L T521 View Post
    So what you want is _{15}C_3=\frac{15!}{3!(12!)}
    No actually in this case the answer is _{15}P_{3}=(15)(14)(13).
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  4. #4
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    thanks

    thanks! so much. so is it a combination or permentation?
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  5. #5
    o_O
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    It is a permutation because there you are considering people in a specific order. For example, a committee with John as the president and a commitee with John as a treasurer are different. Order matters.
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  6. #6
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    thanks!

    wow! thanks so much!
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