Variance
What is the variance?
The average of the squared difference from the mean.
What is the symbol for standard deviation?
an O with a little line on the top
-4 squared
16
Square root of 1
1
If everyone at school was 6 feet tall what would the mean be?
6 feet
What is the first step in figuring out the variance?
Calculate the mean
If my standard deviation is high what is that telling me?
Numbers are spread out far from the mean
10 squared
100
Squared root of 25
5
How many 1,000 are in a million?
1,000
What is the second step to finding variance?
Subtract the mean from the data
What does standard deviation tell you?
How far the data is from the standard, or from the mean.
15 squared
225
Square root of 10,000
100
What is 25% of a billion dollars?
250 million
What is the third step to find the variance?
Squared the difference from the mean.
If my standard deviation is zero, what does that tell me?
All the numbers are the same
-11 squared
121
Square root of 1 million
1000
If I wanted to tip my waiter 20% and my total bill was $25.76, what would by bill total be?
Around $31
What is the final step to figure out the variance?
Find the average of the squared difference
If the standard deviation for a problem is 15, and the mean is 20, what is +2 standard deviation from the mean?
50
1000 squared
1 million
Square root of 25,000,000
5,000
$23.99