Results 1 to 2 of 2

Math Help - percentile help with CDF

  1. #1
    Junior Member
    Joined
    Sep 2009
    Posts
    47

    percentile help with CDF

    I need to understand part b.

    how did they get n(p)

    in other words, how did they go from
    p = F(n(p)) ......to n(p)

    see the attachment!
    Attached Thumbnails Attached Thumbnails percentile help with CDF-capture.jpg  
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor matheagle's Avatar
    Joined
    Feb 2009
    Posts
    2,763
    Thanks
    5
    That's just the quadractic equation. Let x be the p^{th} percentile

    so p=F(x) or p=2(x+{1\over x} -2)

    multiply by x and create a quad equation

    px=2(x^2+1 -2x)

    x^2 -(2+{p\over 2})x+1=0

    NOW solve for x and discard the bad solution.
    Last edited by matheagle; November 6th 2009 at 10:36 PM.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. n-th percentile
    Posted in the Statistics Forum
    Replies: 5
    Last Post: June 7th 2010, 11:28 AM
  2. percentile help
    Posted in the Advanced Statistics Forum
    Replies: 1
    Last Post: November 6th 2009, 12:29 PM
  3. percentile
    Posted in the Math Topics Forum
    Replies: 3
    Last Post: August 8th 2009, 05:14 PM
  4. Percentile
    Posted in the Statistics Forum
    Replies: 1
    Last Post: June 23rd 2009, 01:37 PM
  5. percentile
    Posted in the Statistics Forum
    Replies: 1
    Last Post: October 16th 2008, 09:36 AM

Search Tags


/mathhelpforum @mathhelpforum