Results 1 to 4 of 4

Math Help - Factorials 2

  1. #1
    Senior Member
    Joined
    Nov 2008
    Posts
    425

    Factorials 2

    Ten people are to be seated at a rectangular table for dinner. Tanya will sit at the head of the table. Henry must not sit beside either Wilson or Nancy. In how many ways can the people be seated for dinner?

    this is my work, but does not lead me to the correct answer:

    7! x 2 x 2 = 20160

    The answer they have is 201600
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor

    Joined
    Aug 2006
    Posts
    18,966
    Thanks
    1785
    Awards
    1
    Quote Originally Posted by skeske1234 View Post
    Ten people are to be seated at a rectangular table for dinner. Tanya will sit at the head of the table. Henry must not sit beside either Wilson or Nancy. In how many ways can the people be seated for dinner?
    The answer they have is 201600
    That is not the answer that I get.
    I done it three different ways and get 211680.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Senior Member
    Joined
    Nov 2008
    Posts
    425
    Quote Originally Posted by Plato View Post
    That is not the answer that I get.
    I done it three different ways and get 211680.

    How did you get your answer of 211680

    I have:

    9! - (8! x 2) - (8! x 2)
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor

    Joined
    Aug 2006
    Posts
    18,966
    Thanks
    1785
    Awards
    1
    Quote Originally Posted by skeske1234 View Post
    How did you get your answer of 211680
    I have:
    9! - (8! x 2) - (8! x 2)
    If you do that way then you have removed the case where Henry sits between Wilson and Nancy, NHW or WHN, twice.
    Using inclusion/exclusion we get:
    9!-4\cdot(8!)+2\cdot(7!)
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Factorials
    Posted in the Discrete Math Forum
    Replies: 3
    Last Post: November 2nd 2009, 12:35 PM
  2. Factorials
    Posted in the Math Topics Forum
    Replies: 1
    Last Post: May 24th 2009, 10:13 PM
  3. factorials
    Posted in the Algebra Forum
    Replies: 1
    Last Post: March 27th 2009, 06:53 PM
  4. Getting rid of factorials
    Posted in the Algebra Forum
    Replies: 2
    Last Post: January 14th 2009, 11:04 AM
  5. factorials
    Posted in the Number Theory Forum
    Replies: 2
    Last Post: June 24th 2006, 07:32 PM

Search Tags


/mathhelpforum @mathhelpforum