Results 1 to 2 of 2

Math Help - Statistic assistance needed!!!

  1. #1
    Newbie
    Joined
    Mar 2008
    Posts
    5

    Statistic assistance needed!!!

    .A study of the amount of time it takes a mechanic to rebuild the transmission for a 1998 Acura Integra shows that the mean is 8.4 hours and the standard deviation is 1.8 hours. If 40 mechanics are randomly selected, find the probability that their mean rebuild time exceeds 8.1 hours. u=8.4 o=1.8/√40
    Z= -u Z= 8.1 -8.4 = -0.3 = -1.05 P=0.1469 found by .5000-0.3531
    o√n 1.8/√40 0.285

    Is this correct
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by Seansgirl1 View Post
    .A study of the amount of time it takes a mechanic to rebuild the transmission for a 1998 Acura Integra shows that the mean is 8.4 hours and the standard deviation is 1.8 hours. If 40 mechanics are randomly selected, find the probability that their mean rebuild time exceeds 8.1 hours. u=8.4 o=1.8/√40
    Z= -u Z= 8.1 -8.4 = -0.3 = -1.05 P=0.1469 found by .5000-0.3531
    o√n 1.8/√40 0.285

    Is this correct
    No. How can Pr( X > 8.1) possibly be less than 0.5 when 8.1 < 8.4 = mean??

    The answer, correct to four decimal places, is 0.8541.

    The typesetting of your work makes it too difficult for me to follow your work and point out your mistake(s).

    This question has been replied to here: http://www.mathhelpforum.com/math-he...ssistance.html
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 2
    Last Post: February 16th 2011, 05:26 PM
  2. Transposing Equations Assistance Needed
    Posted in the Algebra Forum
    Replies: 11
    Last Post: February 11th 2011, 09:24 AM
  3. Assistance is needed.
    Posted in the Math Topics Forum
    Replies: 7
    Last Post: October 8th 2008, 09:46 AM
  4. Statistic assistance needed!!!
    Posted in the Advanced Statistics Forum
    Replies: 1
    Last Post: April 22nd 2008, 05:32 PM
  5. Assistance needed: Measure theory
    Posted in the Calculus Forum
    Replies: 0
    Last Post: November 29th 2006, 05:38 AM

Search Tags


/mathhelpforum @mathhelpforum