1. Limited time only! Sign up for a free 30min personal 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

Similar Threads - Basic Score Standard Date
Basic First ODE and Separation problem Dec 28, 2017
Basically solved, Last coordinate does not match? Oct 7, 2017
Basic limits Jun 17, 2017
Basic integration Jun 16, 2017
A normal distribution of IQ scores Oct 19, 2015