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Homework Help: Permutations problem

  1. Apr 22, 2013 #1
    1. The problem statement, all variables and given/known data

    1.) 4 of the books have red covers, 3 have green covers, and another 2 have gray covers. In how many ways can the books be arranged on a shelf if books of the same color must be arranged together?

    3. The attempt at a solution

    1) I think that the answer here is 3!

    But here is the answer from my book (4!3!2!)3!
  2. jcsd
  3. Apr 22, 2013 #2


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    Hi Government$! :smile:
    That's correct only if books of the same colour are stuck together! :wink:
  4. Apr 22, 2013 #3
    If the answer they are looking for is 4!3!2!3! it would have been less ambiguous to pose the question as "There are 9 different books. 4 of the books have red covers...".
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