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# HELP! Stats Problemo....

Hey there people

Helping my nephew with a question he was set....He is given no data just the average and the questions asks him work out the standard deviation from that.

How is that possible as I remember you needed all the data from where youy worked out the average and then work out standard deviation!?

Any Idea...

do you have the numbers that make up that average or the sample size?

You can't work out standard deviation from just the average. SD is a measure of how far the items deviate from the average, so using the average alone as a measurement can never give anything but 0 - one number can't deviate from itself.

Original Poster

Hi there

I square rooted the average given and got the answer :thumbsup:

Wooooo

Thanks for you replies anyway!

the question they gave you must have been wrong, should have said variance rather than average

SkippyDoo;1721012

Hi thereI square rooted the average given and got the answer … Hi thereI square rooted the average given and got the answer :thumbsup:WoooooThanks for you replies anyway!

you can't square root an average.
What you had was an average of the sum of each of the deviations squared.