$ 解：(1) \bar{x_{甲}}=\frac {1.70+1.65+1.68+1.69+1.72+1.73+1.68+1.67}8=1.69(\mathrm {m})$
$ \bar{x_{乙}}=\frac {1.60+1.73+1.72+1.61+1.62+1.71+1.70+1.75}8=1.68(\mathrm {m})$
$ s²_{甲}=\frac 18［(1.70-1.69)²+(1.65-1.69)²+...+(1.67-1.69²)］=0.0006(m²)$
$ s²_{乙}=\frac 18［(1.60-1.68)²+(1.73-1.60)²+...+(1.75-1.60)²］=0.00315(m²)$
$ (2)∵ s²_{甲}＜s²_{乙}∴甲的成绩更稳定.$
$ (3)（更多请点击查看作业精灵详解）$
