# Notes: Standard Deviation

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Notes: Standard Deviation
Vocabulary:
1. Standard Deviation- _________________________________________________________________________________________________
__________________________________________________
Symbol = _______________________________________________
2. Variance- _____________________________________________________________________________________________________________
3. Population- __________________________________________________________________________________________________________
4. Sample- ______________________________________________________________________________________________________________
*
*As
=0
gets bigger
__________________________________________________
__________________________________________________
When is it Used?
 Weather: Maximum temperatures for two cities. May be the same temperature on a
given day; however, coastal city will have a higher standard deviation than an inland
city making less certainty for the inland city potential high temp.
 Finance: Standard deviation measures risk and uncertainty of future returns. Higher
standard deviation of closing prices yields less certainty for potential investments.
Formula:
Example: Sam has 20 rose bushes. The number of flowers on each bush is:
9, 2, 5, 4, 12, 7, 8, 11, 9, 3, 7, 4, 12, 5, 4, 10, 9, 6, 9, 4
Find the standard deviation.
1.  = mean of all values
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