مجموع انحرافات قيم البيانات عن وسطها الحسابي يساوي صفراً يعني:
a.
sum from i equal 1 to n of open parentheses X subscript i minus top enclose X close parentheses equal 0
b.
sum from blank to blank of open parentheses X subscript i plus top enclose X close parentheses equal 0
c.
sum from i equal 1 to n of open vertical bar X subscript i minus top enclose X close vertical bar equal 0
d.
sum from i equal 1 to n of open parentheses X subscript i minus top enclose X close parentheses to the power of 2 equal 0