如题所述
平均值 : Ex = (x1+x2+. . . +xn)/n
方 差: D(x) = [(x1-Ex)²+(x2-Ex)²+ . . . +(xn-Ex)²]/n
标准差: σ = √D(x)
举例:
x = {1,2,3,4,5}
Ex = 3
D(x) =[(-2)²+(-1)²+0+1+4 ]/5 = 10/5 = 2
σ = √D(x) = √2