1. 15.10 Mean, Variance, & Standard Deviation

2. Mean, Variance & Standard Deviation
Mean = Average of the Data
Add up and Divide by # of data points
Denoted by
Variance: (number-mean)2, add up, divide
Standard Deviation is square root of Variance: denoted by
“the sum of”

3. Normal Distribution Curve (Just look—don’t write)

4. Ex 1) The leading number of home runs in MLB for one season were: 43, 50, 52, 56, 70, 65, 50, 73, 57, 47, & 48
Find the Mean, Variance, & Standard Deviation
1) Mean: Add them up & Divide by 11:

5. Ex 1) The leading number of home runs in MLB for one season were: 43, 50, 52, 56, 70, 65, 50, 73, 57, 47, & 48
Find the Mean, Variance, & Standard Deviation 2) Variance: Find the difference between each value in the set of data and the mean Square them , Add them & Divide by # of data (n) x 43 50 52 56 70 65 73 57 47 48
Total
–13 –6 –4 14 9 –6 17 1 –9 –8
169 36 16
196 81 36
289 1 81 64
969

6. Ex 1) The leading number of home runs in MLB for one season were: 43, 50, 52, 56, 70, 65, 50, 73, 57, 47, & 48
Find the Mean, Variance, & Standard Deviation
3) Standard Deviation: Take square root of Variance

7. T.O.O. Ex 2) Find the mean, variance, and standard deviation:
1, 4, 6, 6, 7, 8, 8, 8 x 1 4 6 7 8
Total –5 –2 1 2 2 2 25 4 1 4 4 4 42

8. Ex 3) What happens to the Mean, V, and SD when we add 2 to each number in previous problem?
1, 4, 6, 6, 7, 8, 8, 8
 3, 6, 8, 8, 9, 10, 10, 10 x 3 6 8 9 10
Total –5 –2 1 2 2 2 25 4 1 4 4 4 42
Mean increases by 2 also!
Var & SD stay same!

9. #9 WS Mean, Variance, & Standard Deviation CST QUIZ!!!!!
Homework
#9 WS Mean, Variance, & Standard Deviation CST QUIZ!!!!!