# Quantitative Method - unknown variance

Hi Guys,

I am preparing for cfa level 1 in December and started with quantitative method i have question.

how can i know the the unknown variance from the question especially if the N less than 30  ?

i will appreciate if someone can help me.

thanks

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I’m not sure I understand your question. You don’t need to know the variance of the population to infer what the value of a particular parameter might be…. however you do need to take into account the number of observations you have and whether you believe the underlying population distribution is normally distributed or not.

Maybe someone else can add to this if I missed something.

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Omarmo39 wrote:
how can i know the the unknown variance … ?

You can’t; that’s what “unknown” means.

Simplify the complicated side; don't complify the simplicated side.

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Hello,

Please precise your question. Why do you need to know the variance of the population ? Is it requested in the question ? If so, please post the question.

Thanks,

i guess you want to know if the number of samples in the question is given or not. If so, sample size is always clearly stated in the question.

Mushfig wrote:

i guess you want to know if the number of samples in the question is given or not. If so, sample size is always clearly stated in the question.

The CFAI won’t likely give you a problem with multiple samples. You’ll probably have one sample with a stated sample size.

Oups.My bad.this is  actually what i was trying to say.Thanks for the correction:)

Mushfig wrote:

Oups.My bad.this is  actually what i was trying to say.Thanks for the correction:)

Ah, sorry for the confusion since that was what you meant! Glad to help