If the mean of the observations x1, x2....,xn is ,
Hello,\(\sum_{i=1}^n\ ( x_{i} -\overline{x})\\ =\sum_{i=1}^n\ x_{i} -\ \overline{x}\ \sum_{i=1}^n\ 1\\ =n*\overline{x}- \overline{x}*n=0\)
