若x1,x2,x3.xn的平均数为m
则方差s^2=1/n[(x1-m)^2+(x2-m)^2+.+(xn-m)^2]
标准差s=√1/n[(x1-m)^2+(x2-m)^2+.+(xn-m)^2] 若x1,x2,x3.xn的平均数为m
则方差s^2=1/n[(x1-m)^2+(x2-m)^2+.+(xn-m)^2]
标准差s=√1/n[(x1-m)^2+(x2-m)^2+.+(xn-m)^2]