find the range and the standard deviation.

Question

For each of the data sets, find the range and the standard deviation.

The measured concentration of a sodium hydroxide ( NaOH ) solution: 0.01008 M , 0.01002 M , 0.00993 M , 0.01015 M , and 0.01002 M .

range:____M standard deviation:_____M

The percentage of iron determined in an ore sample: 22.0%, 20.4%, 17.0%, and 20.4%.

range:____M standard deviation:_____M

Answer 1

If you have a TI-84, finding standard deviation is simple. You plug the numbers into a list and then, at the push of a button, you get standard deviation. If not, to do it manually, is a lot harder. I'll assume you have a TI-84:

Push the "stat" button (four up from "8") You'll have "EDIT" and "1: Edit" highlighted so push "enter". This will bring up your lists. In the L1 column, type in the number. It will look like this:

L1

-------

0.01008

0.01002

0.00993

0.01015

0.01002

Then push the "stat" button again and scroll to the right to "CALC". You will have "1: 1-Var Stats" highlighted so just push "enter"

You will get a screen entitled "1-Var Stats" that says:

List: L1 (make sure this says L1 because that's where you typed in your data. If it doesn't hit "list" and select L1)

Then scroll down to "Calculate" and hit "enter".

It will give you a bunch of information. The 5th one down (σx) is the standard deviation. So, the correct number is 7.293833x10^-5 or 0.00007293833

The range must be calculated. It is the maxX - minX or 0.01015 - 0.00993 = 2.2x10^-4 or 0.00022

Repeat the process for the 2nd problem