# How to Find Q1, Q3 and the Interquartile Range TI 89 calculator

Probability and Statistics Index > TI-89 statistics > Interquartile Range TI 89

TI-89

## How to Find Q1, Q3 and the Interquartile Range TI 89

In order to calculate the IQR by hand, you would have to do a few separate calculations, including finding the mean. The interquartile range formula is Q3-Q1, where Q3 is the third quartile (75%) and Q1 is the first quartile (25%). You could use the online interquartile calculator found on this site. However, you can’t bring the internet to a test, and it’s easy to make errors when calculating by hand. That’s where the TI-89 calculator comes in handy.

## Interquartile range TI 89: Steps

Watch the video or read the steps below:

Sample problem: Find Q1, Q3, and the IQR for the following list of numbers: 1, 9, 2, 3, 7, 8, 9, 2.

Step 1: Press . Scroll to Stats/List Editor (use the arrow keys on the keypad to scroll). Press . If you don’t have the stats/list editor you can download it here.

Step 2: Clear the list editor of data: press F1 8.

Step 3: Press ALPHA 9 ALPHA 1 ENTER. This names your list “IQ.”

Step 4: Enter your numbers, one at a time. Follow each entry by pressing the ENTER key. For our group of numbers, enter
1,9,2,3,7,8,9,2

Step 5: Press F4, then ENTER (for the 1-var stats screen).

Step 6: Tell the calculator you want stats for the list called “IQ” by entering ALPHA 9 ALPHA 1 into the “List:” box. The calculator should automatically put the cursor there for you. Press ENTER twice.

Step 7:Read the results. Q1 is listed as Q1X (in our example, Q1X=2). Q3 is listed as Q3X (Q3X=8.5). To find the IQR, subtract Q1 from Q3 on the Home screen. The IQR is 8.5-2=6.5.

That’s it!

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How to Find Q1, Q3 and the Interquartile Range TI 89 calculator was last modified: October 5th, 2015 by