Results 1 to 2 of 2

Math Help - Probability with Z Score

  1. #1
    Junior Member
    Joined
    Sep 2010
    Posts
    60

    Probability with Z Score

    Hey there, I have two fairly simple questions for you, one I have an answer that id like checked, the other I need more help with

    Women's Weight are normally distributed with a mean of 143 & a standard deviation of 29lb.
    a)If one woman is randomly Selected, find the probability that her weight will be GREATER than 150 lbs


    The way I did this is as follows:

    P(X>150)

    P((x-143)/29)>(150-143)/29))

    I solved the one on the right and got .24137931, which is in relation to a z score. I have a chart for this, and I look up .24 and get a probability of .5948. I want everything on the other side right, so I subtract that from 1 and get .4052(or 41%) as my answer

    Did I do it correctly? I have no way to check my work.

    Women's Weight are normally distributed with a mean of 143 & a standard deviation of 29lb.
    b) Find the probability that 12 randomly selected women will have a mean that will be GREATER than 150 lbs

    This one is very confusing to me, and im not entirely sure where to start.

    EDIT:

    So after some thinking and searching i tried the following (still need someone to check it, as I have no way to myself)

    to get the new standard deviation i did 29/12^(1/2) (square root of 12)

    8.3715789, which I rounded up to 8.4

    (150-143)/8.4 = 0.833333333

    I look at my chart for .83 and get .7939

    Then 1-.7939 to get .2061, or 21%



    I appreciate all help that comes my way
    Last edited by NecroWinter; March 20th 2011 at 02:40 PM.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Senior Member Sambit's Avatar
    Joined
    Oct 2010
    Posts
    355
    Don't be afraid; you got both right
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Probability/Z-Score Question
    Posted in the Statistics Forum
    Replies: 1
    Last Post: October 13th 2011, 07:02 PM
  2. Z-Score and probability
    Posted in the Statistics Forum
    Replies: 5
    Last Post: July 14th 2011, 10:07 PM
  3. probability involving z-score
    Posted in the Advanced Statistics Forum
    Replies: 5
    Last Post: July 27th 2010, 09:18 PM
  4. Z-score Probability
    Posted in the Advanced Statistics Forum
    Replies: 1
    Last Post: December 6th 2009, 02:27 AM
  5. Probability to X-score
    Posted in the Advanced Statistics Forum
    Replies: 1
    Last Post: June 27th 2008, 10:08 PM

Search Tags


/mathhelpforum @mathhelpforum