AQA S1 Standard Deviation please help ;-;

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catfanny
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LOL a bit late for this but seeing as my exams tomorrow morning
When do you divide by √n to find standard deviations?
Like in normally distributed confidence interval questions, when there is a random sample of 5, you divide the population sd by √5.
When else do you do this, and also when do you divide by just n and when do you not divide at all?
Do you do in binomial distribution with √np(1-p) eg (√np(1-p))√n ??
Alsooooooo when using scientific calculators to work out means from tables, do you use sx or σx? (STAT > (A+BX) > VAR > sx or σx???)

Thanks
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Kevin De Bruyne
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(Original post by catfanny)
LOL a bit late for this but seeing as my exams tomorrow morning
When do you divide by √n to find standard deviations?
Like in normally distributed confidence interval questions, when there is a random sample of 5, you divide the population sd by √5.
When else do you do this, and also when do you divide by just n and when do you not divide at all?
Do you do in binomial distribution with √np(1-p) eg (√np(1-p))√n ??
Alsooooooo when using scientific calculators to work out means from tables, do you use sx or σx? (STAT > (A+BX) > VAR > sx or σx???)

Thanks
I'm struggling here, I'm not sure if what you said is true.

For a normally distributed population you don't divide the sd by anything for the distribution of points, in the distribution of the mean you divide the sd by sqrtn...

Perhaps this comes from me being unfamiliar with AQA
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catfanny
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(Original post by Kevin De Bruyne)
I'm struggling here, I'm not sure if what you said is true.

For a normally distributed population you don't divide the sd by anything for the distribution of points, in the distribution of the mean you divide the sd by sqrtn...

Perhaps this comes from me being unfamiliar with AQA
Tbh I probably made half that stuff up in confusion, I don't think I was thinking properly last night lool so nevermind. I just did my S1 exam and all that stuff I asked was quite irrelevant too, so its calm. Thanks for trying to help tho :h:
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