# Tutoring high school statistics, some of my students use the TI-83 Plus. The tutor shows one way to find the mean, median, and standard deviation on it.

Of course, to find the mean, median, or standard deviation of a list of numbers on a calculator, you first have to enter them. As far as I can tell, the TI-83 Plus insists that you do so in a list. Therefore, it really helps to be comfortable with list creation and the list menus if you want to get the mean, median, and standard deviation on the TI-83 Plus.

**Example**: Find the mean, median and standard deviation of the list of numbers

{-10.2, 55, 67, 100.9, 36, 120, -66}

Solution: There are several ways to do this. We’ll focus on one way in this post.

Step 1: In between curly brackets, which you access by 2nd ( or 2nd ), enter the numbers, separated by commas. The comma key is just left of the left bracket key. Key in

2nd ( -10.2, 55, 67, 100.9, 36, 120, -66 2nd )

Step 2: Press the STO> button.

Step 3: Think of a name for your list. I called mine SUSAN. To key in the letters, first press 2nd, then the green ALPHA key. This will lock the keys in ALPHA mode. To name mine SUSAN, I keyed in the following:

2nd ALPHA LN 5 LN MATH LOG. You’ll see the letters in green above those keys.

Step 4: Press ENTER.

On my calculator, after I’ve successfully entered my list, it reprints across the screen. By pressing the blue sideways arrow keys (top right of the keypad), I can scroll through the list to check the values.

Assuming you’ve successfully entered the list, the hard part’s done:)

Step 5: To find the mean of the list, press 2nd STAT, then arrow across the top to the MATH choice.

Step 6: Press 3, which is the mean( option.

Step 7: Press 2nd STAT, then scroll down until you find your list name. Press ENTER to select it.

Step 8: You’ll find you’re back at the main screen. In my case, it says mean(lSUSAN. Close the bracket, then press ENTER.

Hopefully, you receive the answer 43.242857…

Step 9: To find the median, press 2nd STAT to return to the LIST menu. Once again, arrow over to MATH. You’ll see median( as choice 4. Key in 4.

Step 10: Retrieve your list by keying in 2nd STAT, then scrolling down to your list name and pressing ENTER to choose it.

Step 11: Back at the main screen again, I see median(lSUSAN. Close the bracket and press ENTER.

Hopefully, you receive the answer 55.

To find the standard deviation, key in 2nd STAT, then arrow over to MATH. You’ll see stdDev( is choice 7. Key in 7 to select it, then key in 2nd STAT and scroll down to your list. Press ENTER to choose your list. Back at the main screen, close the bracket and press ENTER.

Hopefully, you receive the answer 64.2407….

There are other ways to accomplish the same results on the TI-83 Plus. For more about them, and much more about using the TI-83 Plus in general, look to future posts:)

Source: TI-83 Plus GUIDEBOOK, Texas Instruments, 1999.

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

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