I very happy to register in this forum ...

and I need to some help to find this proof ..

from the properties ofarithmetic meanfor grouped data :

http://www14.0zz0.com/2009/11/30/17/304447025.gif

I need to the proof ...

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- Nov 30th 2009, 08:54 AMfrom saudi arabianew member need to help
I very happy to register in this forum ...

and I need to some help to find this proof ..

from the properties of**arithmetic mean**for grouped data :

http://www14.0zz0.com/2009/11/30/17/304447025.gif

I need to the proof ... - Nov 30th 2009, 10:04 AMGrandad
Hello from saudi arabia

Welcome to Math Help Forum!The formula for the mean is:$\displaystyle \bar{x}=\frac{\sum_{i=1}^nf_ix_i}{\sum_{i=1}^nf_i}$Grandad

$\displaystyle \Rightarrow\bar{x}\sum_{i=1}^nf_i=\sum_{i=1}^nf_ix _i$

$\displaystyle 0=\Rightarrow\sum_{i=1}^nf_ix_i-\sum_{i=1}^nf_i\bar{x}$

$\displaystyle \Rightarrow\sum_{i=1}^nf_i(x_i-\bar{x})=0$

- Nov 30th 2009, 10:57 AMfrom saudi arabia
I very thank Mr Grandad to help me..

because I have three days to search in arabic sites .. and I have statistic exam ..