∵甲=(40+39.8+40.1+40.2+39.9+40+40.2+39.8+40.2+39.8)=40mm, 乙=(40+40+39.9+40+39.9+40.2+40+40.1+40+39.9)=40mm, ∴S2甲=[(40-40)2+(39.8-40)2+(40.1-40)2+(40.2-40)2+(39.9-40)2+(40-40)2+(40.2-40)2+(39.8-40)2+(40.2-40)2+(39.8-40)2]=0.026(mm)2, S2乙=[(40-40)2+(40-40)2+(39.9-40)2+(40.2-40)2+(40-40)2+(39.9-40)2+(40.2-40)2+(40-40)2+(40.1-40)2+(40-40)2+(39.9-40)2]=0.008(mm)2, ∵S2甲>S2乙, ∴乙机床的性能更好些. |