(100+98+110+89+103)/5=100
S^2=1/5*[(100-100)^2+(89-100)^2+(110-100)^2+(98-100)^2+(103-100)^2]
=1/5*(121+100+4+9)
=46.4
(86+100+98+119+97)/5=100
S^2=1/5*[(100-100)^2+(98-100)^2+(86-100)^2+(119-100)^2+(97-100)^2]
=1/5*(4+121+361+9)
=98.6
第二组的方差大.