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# How to calculate Standard deviation

I have lots of data -21 people with various info on each- I need to compare data for each via gender, age, etc.. but my problem is that I need to do this by using standarad deviations- I have tried numerous sites to figure how to do this- But every site uses charts- I need an example that is similar to my problem-using #'s not charts
For example 9 dogs with all different weights or any other #'s you wish to assign
I just need to know ( in laymans terms) step by step how to calculate it. I need to find the class avg + or - SD, Female avg + or - SD, and Male avg + or - SD
My example in my book just gives the following
n=numer of data values in
x-value of each data point (what is a data point)?
Z=mean
than calcuate the mean
subtract the mean from each x value
square each Z-x value
add all squared values and this is the sum of squares
then n-1

Then I will need to graph this info- I haven't got a clue on how to do this. Can you help?

#### Solution Summary

Gives step by step instruction to calculate standard deviation.

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