# normal distribution to approximate

• Jun 1st 2009, 05:12 PM
jennifer1004
normal distribution to approximate
How do I find $P(Z \le -0.9)$? I think it is the same as $P(Z \ge 0.9)$. So then, do I just find $\Phi$0.9 and subtract it from 1? (1-0.8159=0.1841)
• Jun 1st 2009, 05:17 PM
pickslides
(Nod)
• Jun 1st 2009, 05:57 PM
matheagle
I really like these online stat calculators.
They give p-values and they have all kinds of densities, t, F...
Free Cumulative Area Under the Standard Normal Curve Calculator
Plugging in -.9 give a probability of .1840601 and you can see a pretty picture too.
• Jun 1st 2009, 07:29 PM
jennifer1004
Thank you so much! That calculator definitely will come in handy.
• Jun 1st 2009, 08:09 PM
matheagle