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Permutation or combination =(?help here pls

  1. Mar 3, 2009 #1
    idk if i should post this question here as i couldnt find any specific forum to post at homework section this has to do with statistics. the question is:

    Question: The Board of a company consists of 4 men and 4 women.The 8 directors are to stand in a straight line so that a photo can be taken.
    a)calculate the number of difft. ways in which the 8 directors can be arranged in a line.
    b)in how many ways can the directors be arranged so that in the line the men and women stand alternately.
    c) 5 members of the board of directors are to be chosen to form a committee .there must be atleast 2 women in the committee.find the number of different committee that could be chosen.

    =( confused sos pls, could some1 guide me thro as where to use npr or npc.tyvm in advance and if i have posted the wrong place could the moderators shift it to its appropriate place
  2. jcsd
  3. Mar 3, 2009 #2
    The big difference is whether order is respected. You have to ask yourself, if you change the order of two arrangements/committtes/lists/pools/groups/tables/etc, are they still the same? Permutations are used when changing the order means the things are no longer equal. Combinations are used when changing the order has no effect on the equality.
  4. Mar 3, 2009 #3
    k, so how shall i start with the 1st bit?so would the 1st one be permutation?
  5. Mar 3, 2009 #4
    I would say so.
  6. Mar 3, 2009 #5
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