Finding Standard Deviation

1.)  Enter the five numbers into the graphing calculator.  To do this, press STAT, and then press enter.

2.)  Enter in your data in the column that says “L1.”

3.)  Press STAT again, and this time press the right arrow to move over the Calc menu.  Select the first option, 1-Var Stats, and press ENTER.

4.)  Press 2nd, 1 to select L1.  The home screen should read “1-Var Stats L1.”  This command is telling the calculator to find out some information about the data you just entered.  Then press ENTER.

The fifth number down is the standard deviation.  Standard deviation is represented by the Greek letter sigma, which looks like a man wearing a hat.

Let’s say you want to find the standard deviation of the set of data {72, 81, 83, 100, 96} on your graphing calculator.  If you follow this process, the standard deviation will be 10.249 when rounded to the nearest thousandth.

Finding Variance

Variance is just the standard deviation, squared.

To find the variance, enter in the standard deviation into your calculator.  Then press the x-squared button.  The answer is the variance!

If the standard deviation is 10.249, then the variance is 105 when rounded to the nearest whole number.

On your own

Find the variance to the nearest tenth, and standard deviation to the nearest hundredth, of {96, 92, 88, 71, 83, 87, 79, 85, 99, 89}.

The answers are at the end of the video!