(1)平均数是( 10+ 10.1 +9.7+ 9.9 +10.3)/5=10
s²=1/5*[(10-10)^2+(10.1-10)^2+(9.7-10)^2+(9.9-10)^2+(10.3-10)^2]
=1/5*[0+0.01+0.09+0.01+0.09]
=1/5*0.2
=1/25
(2)平均数是( 1-2+0-1+1)/5=-1/5= -0.2
s²=1/5*[(1+0.2)^2+(-2+0.2)^2+(0+0.2)^2+(-1+0.2)^2+(1+0.2)^2]
=1/5*[1.44+3.24+0.04+0.64+1.44]
=1/5*6.8
=1.36