Results 1 to 2 of 2

Math Help - Permutations and Combinations

  1. #1
    Member
    Joined
    Oct 2011
    Posts
    170
    Thanks
    3

    Permutations and Combinations

    So I havea really bad worded question in my opinion... It reads

    1a) Given the word leak, calculate the number of permutations:

    I wrote 24 because 4! = 24

    1b) Calculate the number of 2-letter unordered combinations:

    I wrote 6 because 24 / 2 = 12 then half 12 because it's asking for unordered combinations.

    2c) By writing out all the permutations and all the 2-letter unordered
    combinations, show that the two methods described above give the same result,
    and that the number of results are consistent with the numbers you calculated
    above:

    But they don't give the same result.... one gives 24 and the other 6.... what is it asking for exactly?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor

    Joined
    Aug 2006
    Posts
    18,649
    Thanks
    1597
    Awards
    1

    Re: Permutations and Combinations

    Quote Originally Posted by uperkurk View Post
    So I havea really bad worded question in my opinion... It reads
    1a) Given the word leak, calculate the number of permutations:
    I wrote 24 because 4! = 24 CORRECT

    1b) Calculate the number of 2-letter unordered combinations:
    I wrote 6 because 24 / 2 = 12 then half 12 because it's asking for unordered combinations.

    2c) By writing out all the permutations and all the 2-letter unordered
    combinations, show that the two methods described above give the same result,
    and that the number of results are consistent with the numbers you calculated
    above: But they don't give the same result.... one gives 24 and the other 6.... what is it asking for exactly?
    I agree this a poorly put question.

    But unordered combination are \binom{4}{2}=\frac{4!}{2!\cdot 2!}=6.

    I do not understand what 2c) says.
    There 24 permutations and 6 combinations.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Permutations and Combinations
    Posted in the Discrete Math Forum
    Replies: 1
    Last Post: November 23rd 2011, 08:31 AM
  2. permutations and combinations
    Posted in the Statistics Forum
    Replies: 3
    Last Post: August 30th 2011, 08:49 AM
  3. DNA permutations and combinations
    Posted in the Discrete Math Forum
    Replies: 2
    Last Post: July 8th 2010, 02:45 PM
  4. Permutations and Combinations
    Posted in the Discrete Math Forum
    Replies: 3
    Last Post: December 12th 2009, 08:07 AM
  5. Permutations and Combinations
    Posted in the Statistics Forum
    Replies: 1
    Last Post: May 12th 2008, 10:07 AM

Search Tags


/mathhelpforum @mathhelpforum