Average value: M=(x 1+x2+x3+…+xn)/n (n represents the number of this group of data, x 1, x2, x3 …+xn represents the specific value of this group of data) Variance formula: S2; =〈(m-x 1)^2； +(m-x2)^2； +(m-x3)^2； +…+(m-xn)^2； 〉╱n