1. Sect. 8-6-8 Statistics Standard Deviation

2. Def: A measure of the spread or variation of data is called the Standard Deviation which measures how much each value in a set of data differs from the mean.
Steps to find the Standard Deviation
Find the mean
Find the difference between each value in the set of data and the mean
Square the difference
Find the mean of the squares
Take the principal square root of this mean

3. 1) A study about the effects of different fertilizers on tree growth is being conducted. The trees planted last year are now 59 cm, 59 cm, 65 cm, 54 cm, 60 cm, 58 cm, 50 cm and 66 cm tall. Calculate the mean height of the trees and find the standard deviation of the data
Find the mean

4. 1) cont’d: The trees are now 59 cm, 59 cm, 65 cm, 54 cm, 60 cm, 58 cm, 50 cm and 66 cm tall.
b) Find the difference between each value in the set of data and the mean

5. 1) cont’d: The trees are now 59 cm, 59 cm, 65 cm, 54 cm, 60 cm, 58 cm, 50 cm and 66 cm tall.
c) Square the difference
d) Find the mean of the squares

6. 1) cont’d: The trees are now 59 cm, 59 cm, 65 cm, 54 cm, 60 cm, 58 cm, 50 cm and 66 cm tall.
e) Take the principal square root of this mean

7. 2) The U. S. is likely to produce a record 14
2) The U.S. is likely to produce a record billion bushels of corn in the 2013 year. Corn production totaled billion bushels in billion bushels in 2011, which was slightly below the 2010 level of billion bushels. In 2009, a record crop of 13.1 billion bushels was produced. In 2008, billion bushels was produced
Find the mean for the corn production and the standard deviation of the data

8. 2) Data: 14. 27 billion 2013. In 2012. 12. 78 billion 12
2) Data: billion In billion billion in In 2010, billion. In 2009, 13.1 billion, In 2008, billion bushels
Year
Billions of Bushels
Difference from the Mean
Square of the Difference
2008
2009
2010
2011
2012
2013

9. 2) cont’d Find the standard deviation of the data

10. 3) Find the mean and standard deviation for the heights of your classmates in your assigned group

11. Homework
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