Standard deviation as a percentage

#1
Hi i'm new here and have a really quick question,
How do you interpret a standard deviation given as a percentage (in this case 20%)?
I need to use the variance in further calculations (working out type i and ii errors), the data is normally distributed, and the sample size is 30, i have further information but i'm not sure its relevant.
I'm sure the way to proceed is simple, but i'm stuck!!
Any help would be apreciated :)
 

ledzep

Point Mass at Zero
#2
You sure it was standard deviations? It is quite likely that you're given the Coefficient of Variation (CV) , which are reported as percentages.

\( CV= \frac{\sigma}{\mu} \) where \(\sigma\) is your standard deviation and \(\mu\) is your mean.
 
#3
That would make more sense!! But I just checked and it definitely means standard deviation: "with population standard deviation 20%.”
Could it mean that the standard deviation is 0.2*(sample size) = 0.2*(30)? That was my first guess at what to try but I’m not sure there is any mathematical justification!!
Thank you for your reply!!
 
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