1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Basic Z-Score & Standard Normal Question

  1. May 7, 2008 #1
    If Z is a random variable having the standard normal distribution, find

    So I punch it into my calculator nmcdf(-.79,infinity,0,1) & I get the answer .7852

    The book however has the answer .2148 (essentially 1-ans).

    Which is what I don't understand...

    Have I forgotten something really simple, or do you think there is an error in the book. Most of the time its me :(.
  2. jcsd
  3. May 7, 2008 #2
    Also, P(-1.90>z>.44)

    The only thing I could think of was nmcdf(-infinity,-1.90,0,1)+nmcdf(.44,infinity,0,1) which gives .3587 but the book gives the answer .6143.
  4. May 7, 2008 #3


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Are you sure you've written the problems correctly? P(-1.90>z>.44) is obviously zero, no matter how z is distributed.
    Last edited: May 7, 2008
  5. May 7, 2008 #4
    100% sure. I think its an error in the book... I don't really see how it can be possible. If you flip the signs around it makes sense though.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Basic Z-Score & Standard Normal Question