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Why Sum(mean squared) -> n times mean squared. Page 112

#1 User is offline   MB 

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Posted 28 January 2009 - 03:53 AM

Hello,

I need someone to explain to me how Σμ2 ends up as nμ2.

On the third line of the equation, a note says that there are as many "n's" in Σμ2 as in nμ2, but I do not get it.

I will really appreciate any comment or link.

Thanks a lot.
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#2 User is offline   dawng 

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Posted 09 February 2009 - 12:24 AM

Hi MB,

The important thing here is that μ2 is a constant. This means that

Σμ2 = μ2 + μ2 +μ2 + ... + μ2

and there are n of these μ2's. This gives

Σμ2 = nμ2

Hope this helps,

Dawn
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#3 User is offline   MB 

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Posted 09 February 2009 - 02:26 AM

Thank you very much Dawn... Yes, now I understand.
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#4 User is offline   ankitpdr 

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