Results 1 to 3 of 3

Math Help - number of codes

  1. #1
    Newbie
    Joined
    Sep 2008
    Posts
    5

    number of codes

    hey i would really appreciate it if somebody could answer this:

    Assume that product codes are formed from the letters S, W, Q, T, R, and Y, and consist of 4 not necessarily distinct letters arranged one after the other. For example, SSWR is a product code.

    (1) How many different product codes are there?

    i got this one, it's 6^4 because there are 4 stages and each has 6 options.

    (2) How many different product codes do not contain W?

    i got this one too, it's 5^4 because instead of 4 stages with 6 options, there are 4 stages with 5 options.

    (3) How many different product codes contain exactly one R?

    this is the one i haven't been able to get. help please?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Newbie
    Joined
    Jul 2008
    Posts
    12
    The answer is 4 x 5^3

    This is because you have exactly one "R", so you first put an "R" in the product code, and then count the number of places it can be (it can be in four places). Then you have 3 decisions with 5 options for the remaining 3 spots, so you multiply by 5^3.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Sep 2008
    Posts
    5
    thanks. that helps a lot.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Number of 4 digit codes in logarithmic form.
    Posted in the Discrete Math Forum
    Replies: 1
    Last Post: December 7th 2011, 07:14 AM
  2. Total number of codes generated from 8 bit blocks
    Posted in the Number Theory Forum
    Replies: 5
    Last Post: October 14th 2011, 02:22 PM
  3. Codes
    Posted in the Discrete Math Forum
    Replies: 0
    Last Post: August 12th 2010, 02:36 AM
  4. Codes
    Posted in the Number Theory Forum
    Replies: 1
    Last Post: September 9th 2007, 01:06 AM
  5. Some codes . . .
    Posted in the LaTeX Help Forum
    Replies: 2
    Last Post: June 18th 2007, 07:21 PM

Search Tags


/mathhelpforum @mathhelpforum