9514 1404 393
Answer:
make use of the invNorm( ) function
Step-by-step explanation:
The invNorm function is used for this purpose on a TI-84 calculator. It can be selected from the catalog, or from the functions available under the DISTR (2nd VARS) key.
As arguments, it takes (area, mean, standard deviation) and an optional fourth tail parameter indicating whether you want the Z-score corresponding to the left tail (default), the center, or the right-tail area. The tail parameter is available at the bottom of the list under the DISTR key.
__
For the purpose here, we find the left cutoff to be about -1.175. Since the distribution is symmetrical, the right cutoff will be about +1.175.
_____
Additional comment
The attached image is a screen shot of the GraphNCalc83 app available for iOS devices. It emulates a TI-83/84 calculator very well, improving on accuracy and human factors in a number of places. (Disclaimer: I have no financial interest in this app. I just find it very useful.)
