Results 1 to 5 of 5

Math Help - Help with Poisson distribution

  1. #1
    Newbie
    Joined
    Nov 2009
    Posts
    4

    Help with Poisson distribution

    i have a question, if possible, I need some one to help me to solve it. I know it's easy but it kind make me dizzy.

    if a cable is manufactured with probability of 0.001 that has one blemish per foot and probability of 0 for more than a blemish with same length. If X is the number of blemish per 3000 feet, get the Pr(X=5) ??

    is the solution will be as follow:

    mu = n * p = 3000 * .001 = 3

    Pr(X=5) = [ 3^5 * e^(-3) ] / 5! = .100 =10% (Poisson Distribution)
    Last edited by mr fantastic; November 29th 2009 at 05:56 PM. Reason: Changed post title
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member craig's Avatar
    Joined
    Apr 2008
    Posts
    748
    Thanks
    1
    Awards
    1
    Quote Originally Posted by ktoobi View Post
    i have a question, if possible, I need some one to help me to solve it. I know it's easy but it kind make me dizzy.

    if a cable is manufactured with probability of 0.001 that has one blemish per foot and probability of 0 for more than a blemish with same length. If X is the number of blemish per 3000 feet, get the Pr(X=5) ??

    is the solution will be as follow:

    mu = n * p = 3000 * .001 = 3

    Pr(X=5) = [ 3^5 * e^(-3) ] / 5! = .100 =10% (Poisson Distribution)
    Yes that seems correct. Using my tables I get P(X \leq 5) = 0.9161 and P(X \leq 4) = 0.8153, therefore P(x = 5) = P(X \leq 5) - P(X \leq 4) = 0.1008.

    Your answer of 10% seems fine
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Nov 2009
    Posts
    4
    thanx man; you are quick

    can you just explain your answers plz. and which table did u used?
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Super Member craig's Avatar
    Joined
    Apr 2008
    Posts
    748
    Thanks
    1
    Awards
    1
    Quote Originally Posted by craig View Post
    P(x = 5) = P(X \leq 5) - P(X \leq 4) = 0.1008.
    Poisson is a discrete distribution, therefore the values can only be integers, 1,2,3 etc. P(X \leq 5) are the values from 0..5. P(X \leq 4) are the values 0..4.

    This implies that P(x = 5) = P(X \leq 5) - P(X \leq 4).

    The tables that I use are Poisson statistical tables. They are basically a shortcut for working out probabilities without doing the calculations. If your course does not use them though, then I do not recommend using them, as this could have a negative affect when you come to do the calculations the the exams and you've not a clue how to do them

    From what I've seen though you seem to have got to grips with the distribution quite fine.
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Newbie
    Joined
    Nov 2009
    Posts
    4
    1
    Last edited by ktoobi; December 8th 2009 at 05:02 PM.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 1
    Last Post: December 27th 2011, 01:08 PM
  2. Poisson Distribution
    Posted in the Advanced Statistics Forum
    Replies: 3
    Last Post: October 31st 2010, 10:32 PM
  3. Poisson Distribution
    Posted in the Statistics Forum
    Replies: 3
    Last Post: October 7th 2010, 01:12 PM
  4. Poisson distribution and asymptotic normal distribution.
    Posted in the Advanced Statistics Forum
    Replies: 0
    Last Post: August 18th 2010, 05:52 AM
  5. Poisson Distribution Help v2.0
    Posted in the Advanced Statistics Forum
    Replies: 0
    Last Post: November 12th 2008, 01:30 PM

Search Tags


/mathhelpforum @mathhelpforum