Question

If x_i's are the midpoints of the class intervals of grouped data, f_i's are the corresponding frequencies and `barx` is the mean, then `sum(f_ix_i-barx)` is equal to ______.

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Answer 1

If x_i's are the midpoints of the class intervals of grouped data, f_i's are the corresponding frequencies and `barx` is the mean, then `sum(f_ix_i-barx)` is equal to 0.

Explanation:-

`because barx=(sumf_ix_i)/n`

`thereforesum(f_ix_i-barx)=sumf_ix_i-sumbarx`

`=nbarx-nbarx=0`