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Critical z value TI 83: Easy Steps for the InvNorm function

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Critical z value TI 83

Critical z value TI 83
A critical value in hypothesis testing separates the region where the hypothesis will be rejected from the region where the hypothesis will not be rejected. You could use the equation above to find the z-score, but it’s not the easiest equation to look at! With a little arithmetic, you can look up a critical value in a z-table, or you can use the InvNorm function on the TI-83 graphing calculator.

critical z value ti 83 invnorm function

The TI 83 calculator is probably the most widely used calculator in statistics, because of its array of built-in statistical functions.

Find more help for the TI 83 and statistics by visiting the main TI 83 for statistics menu.

Critical z value TI 83: Steps

Sample Problem: An end of semester exam is normally distributed with a mean of 85 and a standard deviation of 10. Find the z score at the 90th percentile with the InvNorm function
Step 1: Press 2nd VARS 3. This displays InvNorm( on the home screen.

Step 2: Type . 9 0 , 8 5 , 1 0.

Step 3: Press the ) button.

Your display should read InvNorm(.9, 85, 1, 0).

Step 4: Press ENTER. This returns 97.82. That means that 90% of students will have scores below 97.82.

That’s it! Like the explanation?

That’s how to find a Critical z value TI 83!

Tip: The first entry on InvNorm should be a number between 0 and 1.

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