Results 1 to 2 of 2

Math Help - Permutations Help

  1. #1
    Banned
    Joined
    Mar 2010
    Posts
    12

    Permutations Help

    how many four digit numbers can you form with the digits 1, 2, 3, 4, 5, 6, 7 if no digit is repeated

    b) How many of these digits are even?
    c) how many of these digits are odd?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member

    Joined
    May 2006
    From
    Lexington, MA (USA)
    Posts
    11,738
    Thanks
    644
    Hello, MHurricane!

    How many f4-digit numbers can you form with the digits 1, 2, 3, 4, 5, 6, 7

    a) if no digit is repeated?

    There are: . _7P_4 \:=\:840 possible 4-digit numbers.



    b) How many of these numbers are even?

    The last (rightmost) digit has 3 choices: {2, 4, 6}

    Choose 3 of the other 6 digits.
    . . They can be arranged in: . _6P_3 = 120 ways.

    Therefore, there are: . 3\cdot120 \:=\:360 even numbers.



    c) How many of these numbers are odd?

    The rest of them: . 840 - 360 \:=\:480 odd numbers.

    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Permutations
    Posted in the Discrete Math Forum
    Replies: 2
    Last Post: December 13th 2009, 05:10 AM
  2. Permutations
    Posted in the Discrete Math Forum
    Replies: 9
    Last Post: November 26th 2009, 09:55 PM
  3. Permutations
    Posted in the Discrete Math Forum
    Replies: 4
    Last Post: October 28th 2009, 02:27 PM
  4. permutations
    Posted in the Number Theory Forum
    Replies: 2
    Last Post: May 18th 2009, 01:38 AM
  5. Permutations
    Posted in the Advanced Algebra Forum
    Replies: 1
    Last Post: October 16th 2008, 06:59 PM

Search Tags


/mathhelpforum @mathhelpforum