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Permutation and combination question.

  1. Dec 15, 2011 #1
    there are n students in a class. They are selected in sets of m. A student says he is selected a times. find value of a in terms of m and n.
    Total number of selections made are nCm.
    After that nothing is striking in my mind.can you please help.
     
  2. jcsd
  3. Dec 15, 2011 #2

    Ray Vickson

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    Start by looking at small example, such as n = 4 and m = 2, 3 or 4. Select an element such as '1', and look at all the subsets that contain that element. Once you see the pattern, it should be easier to look at the general n, m problem.

    RGV
     
  4. Dec 15, 2011 #3
    getting trend how it is happening and understanding how is it happening is different thing & i want to know second one not first one so it will helpful for me if you did it with variables.
    so can any body please do it with variables.
     
  5. Dec 15, 2011 #4

    Ray Vickson

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    The forum rules require you to show your work. You have not done that.

    RGV
     
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