Results 1 to 2 of 2

Math Help - standardizing normal distribution problem

  1. #1
    Junior Member
    Joined
    Oct 2009
    Posts
    68

    standardizing normal distribution problem

    Scores on test are normally distributed with a mean of 68 and a standard deviation of 8. Find the probability that a student scored at least 75 on the test given that the student scored at least 70.


    Is the bound for this question p(70<X<75) ? Seems like it should be p(X>75), but I'm not sure of what to do with the extra given data.
    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 shawli View Post
    Scores on test are normally distributed with a mean of 68 and a standard deviation of 8. Find the probability that a student scored at least 75 on the test given that the student scored at least 70.


    Is the bound for this question p(70<X<75) ? Seems like it should be p(X>75), but I'm not sure of what to do with the extra given data.
    Apply Bayes Theorem:

    \Pr(X > 75 | X > 70) = \frac{\Pr(X > 75 \text{ and } X > 70)}{\Pr(X > 70)} = \frac{\Pr(X > 75)}{\Pr(X > 70)}.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Normal distribution problem
    Posted in the Statistics Forum
    Replies: 3
    Last Post: October 10th 2011, 11:10 AM
  2. A Normal Distribution Problem
    Posted in the Statistics Forum
    Replies: 1
    Last Post: December 12th 2010, 09:18 PM
  3. Normal distribution Problem
    Posted in the Statistics Forum
    Replies: 1
    Last Post: October 27th 2010, 04:36 AM
  4. normal distribution problem
    Posted in the Statistics Forum
    Replies: 1
    Last Post: April 13th 2010, 04:16 PM
  5. Normal distribution problem
    Posted in the Advanced Statistics Forum
    Replies: 10
    Last Post: July 6th 2006, 08:19 PM

Search Tags


/mathhelpforum @mathhelpforum