Question 63585
What is the (a)variance and the (b) standard deviation of the following scores:
51, 55, 61, 62, 68, 71, 71,73, 81, 82, 87, 89, 92, 94, 95, 100 
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Procedure:
1st: Find the mean or average of the numbers. It is 77
2nd: For each of the numbers find the difference between it and 77.
Ex: 
51-77=-26
55-77=-22
etc.
3rd: Square each of those differences:
Ex:
(-26)^2=676
(-22)^2=484
etc.
4th: Add all those squared numbers
EX: 676+484+....
5th: Divide by the number of numbers if you want the population standard dev.
or Divide by one less tan the number of numbers if you want the sample standard deviation.
5th: Take the square root of the result.
RESULT :
Population standard deviation is 14.70969...
Sample standard deviation is 15.19210...
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The variance is the square of the standard deviation.

Cheers,
Stan H.