Variance s = [(x1-x) 2+(x2-x) 2+(x3-x) 2+...+(xn-x) 2]

Xn is the result of the nth time; X is the average of n grades, that is, x = (x1+x2+...+xn) ÷ n.

Variance indicates the degree of dispersion of points. The smaller the variance, the smaller the dispersion of points, and the closer to the average. The specific problem of this problem is that the smaller the variance, the more stable the score.

As for the standard deviation is the root of variance, the truth is the same as variance.