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rock.freak667

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## Main Question or Discussion Point

**[SOLVED] Quick question about finding standard deviation**

Now I know that [tex]\sigma=\sqrt{var(x)}[/tex]

which simplifies to this expression : [tex]\sigma=\sqrt{\frac{1}{N}\sum_{i=1}^{N}(x-\overline{x})^2}[/tex] can someone show me how they got such an expression?

and in chemistry I have to use a standard deviation calculation to get out a problem. Now normally I would use the above equation but my notes tell me to use this equation:

[tex]\sigma=\sqrt{\frac{1}{N-1}\sum_{i=1}^{N}(x-\overline{x})^2}[/tex]

Which one is correct to use? and can someone tell me if this is correct [tex]c_v =\frac{\sigma}{\overline{x}}[/tex] where [tex]c_v[/tex] is the coefficient of variation