• Support PF! Buy your school textbooks, materials and every day products Here!

Basic Z-Score & Standard Normal Question

  • Thread starter kuahji
  • Start date
  • #1
394
2
If Z is a random variable having the standard normal distribution, find
P(Z[tex]\geq[/tex]-.79)

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 :(.
 

Answers and Replies

  • #2
394
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.
 
  • #3
Hurkyl
Staff Emeritus
Science Advisor
Gold Member
14,916
17
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:
  • #4
394
2
Are you sure you've written the problems correctly? P(-1.90>z>.44) is obviously zero, no matter how z is distributed.
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.
 

Related Threads for: Basic Z-Score & Standard Normal Question

Replies
2
Views
4K
  • Last Post
Replies
5
Views
7K
  • Last Post
Replies
1
Views
779
  • Last Post
Replies
0
Views
3K
Replies
6
Views
1K
  • Last Post
Replies
2
Views
3K
  • Last Post
Replies
6
Views
1K
Replies
1
Views
1K
Top