解：$(1)$如下表:
$\text {解: (2) } \bar x_{\text {甲 }}=9 \text { 环 }, \bar x_{\text {乙 }}=9 \text { 环 }, s_{\text {甲 }}^{2}=\frac{2}{3}, s_{\text {乙 }}^{2}=1,$
∵$\bar x_{\text {甲 }}=\bar x_{\text {乙 }}, s_{\text {甲 }}^{2}<s_{\text {乙 }}^{2},$
∴$\text { 甲与乙 }$的平均成绩相同, 但甲发挥得比乙稳定.
