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Homework Help: How many permutations of simple events

  1. Feb 4, 2012 #1
    1. The problem statement, all variables and given/known data

    I am stuck on this problem relating to permutations:

    The first part asks how many ways can 6 people be lined up. This answer, I believe is 6! = 720 ways.

    The second part: If 3 specific persons, among 6, insist on following each other, how many ways are possible?

    The third part: If 2 specific persons, among 6, refuse to follow each other, how many ways are possible?

    The first part is easy, but I don't know how to do the second and third parts. What is the concept involved in solving the second and third parts?

    Thanks for the help!
  2. jcsd
  3. Feb 4, 2012 #2


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    For the second part, just think of the three-people clump as one person, so you have four people that you need to order.
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