question_answer

If \[{{x}_{i}}'s\] are the midpoints of the class intervals of a grouped data, \[{{f}_{i}}'s\] are the corresponding frequencies and \[\overline{x}\] is the mean, then what is \[\sum\limits_{{}}^{{}}{{{f}_{i}}({{x}_{i}}-\overline{x})}\] equal to?

A)  0                    

B)  \[-\,1\]

C)  1                                

D)  2

E)  None of these