
New Member
Finding Z Score of a given AreaHELP!!!
This problem asks me to find the Z Score that corresponds to an area of 0.8925it says that the row value is 1.2 and the column value is 0.04 so the Z Score is 1.24??? How do they come up with 1.2 and 0.04 from 0.8925??? The book does not explain how and I certainly don't see it? Anyone? Thanks
Peggy

Elite Member
Re: Finding Z Score of a given AreaHELP!!!
Look up .8925 in the body of the z table and we see the corresponding value is 1.24
How do they come up with these values?. It is a complicated integral. That is why we use a ztable where they are already figured out for us.
The .8925 is 89.25% of the area under the normal curve. The 1.24 means it is 1.24 standard deviations above the mean.
If you are interested, the integral these are derived from is:
[tex]\frac{1}{\sqrt{2\pi}}\int_{\infty}^{z}e^{\frac{t^{2}}{2}}dt[/tex]
If you use a calculator or computer and plug in z=1.24 in the above integral, you will get .8925 or very close.

New Member
Re: Finding Z Score of a given AreaHELP!!!
Got it now. All I needed to read was "look for .8925 in the BODY of the table and find the corresponding Z score....It was not worded that way and I thought I was missing a stepI certainly am capable of reading a table and I just didn't realize that all they were doing was telling me to read the table going from the body out as opposed to the columns injust more of reading the table.....So now that I spent all of this time on something so simple, I thank you for simplifying that for me. Thanks
Peggy
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