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Homework Help: Grade 12 Permutations

  1. Apr 21, 2005 #1
    Was just wondering if there was a "shorter" method of solving this problem.

    nPr = 60.

    nPr = n!/(n-r)!

    n=?
    r=3

    Works out to be

    n(n-1)(n-2) = 60.

    From here on, what different options do I have? I have several ways of solving it, but was wondering what would be the "easiest" method.
     
  2. jcsd
  3. Apr 21, 2005 #2
    since n is integer, find all the factors of 60, which are 2,3,4,5 and see which 3 consecutive numbers satisfy n(n-1)(n-2)=60
     
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