1. Warm Up
Homework: Standard Deviation Worksheet

2. Guess What? You have another pop quiz!!!!!!!!!! I know you’re saying
Yes! another good grade Or
Yes this is my chance to make a good grade!!!!

3. Today’s Lesson: Standard Deviation
April 25, 2014

4. Recall ………
What is the Measure of Dispersion?

5. Measures of Dispersion
Another Measure of Dispersion is Standard Deviation Standard Deviation – is the measure of how the values in a data set vary, or deviate, from the mean.

6. Here is a formula for Standard Deviation

7. Finding the Mean and the Standard Deviation

8. Finding the Mean and the Standard Deviation
Don’t get too bogged down about the weird looking formula. There are 5 steps that you need to take to find the standard deviation Let’s look at how they completed the table using the data from the example

9. Finding the Mean and the Standard DeviationX 𝒙
12.6
15.1
11.2
17.9
18.2
Step 1: Find the mean ( 𝒙 )

10. Finding the Mean and the Standard Deviation
Step 2: Find the difference between each data value and the mean: (X - 𝑿 ) X 𝑿
X - 𝑿
12.6 15
15.1
11.2
17.9
18.2

11. Finding the Mean and the Standard DeviationX 𝑿
X - 𝑿
(X − 𝑿 ) 𝟐
12.6 15
-2.4
15.1
0.1
11.2
-3.8
17.9
2.9
18.2
3.2
Step 3: Square each difference: (X − 𝑿 ) 𝟐

12. Finding the Mean and the Standard Deviation
Step 4: X 𝑿
X - 𝑿
(X − 𝑿 ) 𝟐
12.6 15
-2.4
5.76
15.1
0.1
0.01
11.2
-3.8
14.44
17.9
2.9
8.41
18.2
3.2
10.24

13. Finding the Mean and the Standard Deviation
Step 5: Take the square root to find the standard deviation
𝐒𝐭𝐚𝐧𝐝𝐚𝐫𝐝 𝐃𝐞𝐯𝐢𝐚𝐭𝐢𝐨𝐧(𝝈)= __________

14. What does this mean?

16. You Try

17. Within how many standard deviations do all of the data values fall?

18. You Try

21. Since you were such wonderful angels today!!!!!!
I will show you another method of doing this with your calculator!!!!!!

22. Using Your Calculator Let’s do a problem
Step 1: Put your data in STAT (use STAT - - Edit) Step 2: Press STAT- - CALC- - 1-Var Stats (For the yellow calculators you will have to press calculate next) – everyone else just press enter again. Your answer is the one with the 𝐒𝐢𝐠𝐦𝐚(𝝈)
Let’s do a problem

23. Let’s get started on our homework or finish our homework!!!!
Happy Friday!!!!
Let’s get started on our homework or finish our homework!!!!