Results 1 to 7 of 7

Math Help - Counting Principles

  1. #1
    Junior Member
    Joined
    Feb 2010
    Posts
    52

    Counting Principles

    Hi, Im having a hard time defining the problem into a working equation

    Forming a Committee: Four people are to be selected at random from a group of four couples. In how many ways can this be done under the following conditions?

    a. The group must have at least one couple

    Thanks
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Junior Member slovakiamaths's Avatar
    Joined
    Apr 2010
    From
    India
    Posts
    41
    Quote Originally Posted by ugkwan View Post
    Forming a Committee: Four people are to be selected at random from a group of four couples. In how many ways can this be done under the following conditions?

    a. The group must have at least one couple

    Thanks
    Ans is : 4*6*5=120
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Junior Member
    Joined
    Feb 2010
    Posts
    52

    Thumbs down

    It is not 120 b/c if I were to chose a combination of 4 people without regard to if they are a couple or not I would get 70.

    nCr = 8C4 = 70

    It is less than this I think.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Junior Member slovakiamaths's Avatar
    Joined
    Apr 2010
    From
    India
    Posts
    41
    ok ans is ^4C_1*^6C_2+^4C_2=66
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Junior Member slovakiamaths's Avatar
    Joined
    Apr 2010
    From
    India
    Posts
    41
    Follow Math Help Forum on Facebook and Google+

  6. #6
    Junior Member
    Joined
    Feb 2010
    Posts
    52
    Please explain your reason b/c the book says the answer is 54, I dont know how it got to 54.

    How u figure it's 66? An explanation of how you broke down the word problem would help greatly. Thanks
    Follow Math Help Forum on Facebook and Google+

  7. #7
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by ugkwan View Post
    Hi, Im having a hard time defining the problem into a working equation

    Forming a Committee: Four people are to be selected at random from a group of four couples. In how many ways can this be done under the following conditions?

    a. The group must have at least one couple

    Thanks
    {8 \choose 4} - (no. of ways choosing the group with no couples).
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Basic Counting Principles
    Posted in the Discrete Math Forum
    Replies: 1
    Last Post: April 11th 2011, 07:18 PM
  2. Fundamental Counting Principles
    Posted in the Discrete Math Forum
    Replies: 10
    Last Post: January 12th 2010, 08:26 AM
  3. [SOLVED] Counting principles
    Posted in the Statistics Forum
    Replies: 2
    Last Post: April 3rd 2009, 03:13 PM
  4. Counting Principles
    Posted in the Statistics Forum
    Replies: 3
    Last Post: April 2nd 2008, 09:23 PM
  5. counting principles
    Posted in the Discrete Math Forum
    Replies: 1
    Last Post: April 26th 2007, 07:06 AM

Search Tags


/mathhelpforum @mathhelpforum