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Counting math problem

  1. Mar 28, 2014 #1
    1. The problem statement, all variables and given/known data

    Calculate the numbers of different selections of 5 letters which can be made from the letters of the word SYLLABUS



    2. Relevant equations



    3. The attempt at a solution

    I thought it would be 8C5 but that's not the answer.

    Any help?
     
  2. jcsd
  3. Mar 28, 2014 #2

    LCKurtz

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    Do the five letters you select have to all be different? That would matter.
     
  4. Mar 28, 2014 #3
    Well I don't think the question said that, so I don't think they would have to be all different.
     
  5. Mar 28, 2014 #4

    AlephZero

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    If you say there are 8C5 different selections, here are two different ones. The first one is
    YLABU
    The second one is also
    YLABU
    but it's not the same as the first one.
    What is different about them? Do you think they should be counted as different?
     
  6. Mar 28, 2014 #5

    LCKurtz

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    Would you count {Y,A,B,U,L} as two different selections if the L was the first L one time and the second L the next time?

    [Edit] I see AlephZero asks the same question.
     
  7. Mar 28, 2014 #6
    Hmmm, I don't think I would, the Ls are the same aren't they?
     
  8. Mar 29, 2014 #7

    AlephZero

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    Correct. The two S's are also the same.

    Review your textbook or course notes for how that changes the answer, if you can't remember or figure it out for yourself.
     
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