Probability and Statistics > TI 89 > Z Score TI 89

Finding a critical value and reading a

**z-table**are an essential part of elementary statistics. Critical values are used for hypothesis tests, and can help you use the standard normal model to make predictions about data. The TI-89 Titanium graphing calculator makes light work of finding these values, because of its built in z-table. The TI-89 Titanium’s Stats/List Editor contains a simple menu where you can look up Z Score in seconds. This article shows you how to find the z-score for a critical value in a left tail. As the normal distribution curve is symmetrical, this will also be the area in a right tail as well. Not sure if your test is a left tailed or right tailed? See “Left Tailed Test or Right Tailed” to help you decide.

Note that you must have the Stats/List Editor installed to be able to make a TI-89 frequency distribution using these instructions.

## Z Score TI 89: Steps

Watch the video or read the steps below:

**Sample problem**: find the z score for α = .012 for a left-tailed test on a standard normal distribution curve.

**Step 1:** Press Apps, scroll to the **Stats/List Editor**, and press ENTER.

If you don’t see the Stats/List Editor, you can download it here. It’s an official TI app and you’ll need to transfer it to your calculator using the cable that originally came with your TI-89.

**Step 2:** Press F5 2 1, to get to the **Inverse Normal** screen.

**Step 3:** Enter .012 in the **Area** box.

**Step 4:** Enter 0 for the mean, μ and 1 for the standard deviation, σ.

**Step 5:** Press ENTER.

**Step 6:** Read the result: the calculator should state “**Inverse = -2.25713**“. This is your z score.

**Tip**: If you are given a mean and standard deviation, enter them in place of 0 and 1 in Step 4.

That’s how to find a z score TI 89!

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This was helpful as well, this is much better than doing the math by hand! Thanks!

This was very helpful. Thank you!

For those trying to do this with the t-distribution, the option on the TI-89 is right below (inverse t…).

Thanks for the info, Zok!