某校为了了解本校学生对航天科技的关注程度,对八、九年级学生进行了航天科普知识竞赛(百分制),并从其中分别随机抽取了20名学生的测试成绩,整理、描述和分析如下:(成绩得分用
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi%3Ex%3C%2Fmi%3E%3C%2Fmath%3E)
表示,共分成四组:
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi%3EA%3C%2Fmi%3E%3Cmn%3E.%3C%2Fmn%3E%3Cmn%3E8%3C%2Fmn%3E%3Cmn%3E0%3C%2Fmn%3E%3Cmtext%3E%E2%A9%BD%3C%2Fmtext%3E%3Cmi%3Ex%3C%2Fmi%3E%3Cmo%3E%26lt%3B%3C%2Fmo%3E%3Cmn%3E8%3C%2Fmn%3E%3Cmn%3E5%3C%2Fmn%3E%3Cmn%3E%EF%BC%9B%3C%2Fmn%3E%3Cmi%3EB%3C%2Fmi%3E%3Cmn%3E.%3C%2Fmn%3E%3Cmn%3E8%3C%2Fmn%3E%3Cmn%3E5%3C%2Fmn%3E%3Cmtext%3E%E2%A9%BD%3C%2Fmtext%3E%3Cmi%3Ex%3C%2Fmi%3E%3Cmo%3E%26lt%3B%3C%2Fmo%3E%3Cmn%3E9%3C%2Fmn%3E%3Cmn%3E0%3C%2Fmn%3E%3Cmn%3E%EF%BC%9B%3C%2Fmn%3E%3Cmi%3EC%3C%2Fmi%3E%3Cmn%3E.%3C%2Fmn%3E%3Cmn%3E9%3C%2Fmn%3E%3Cmn%3E0%3C%2Fmn%3E%3Cmtext%3E%E2%A9%BD%3C%2Fmtext%3E%3Cmi%3Ex%3C%2Fmi%3E%3Cmo%3E%26lt%3B%3C%2Fmo%3E%3C%2Fmath%3E)
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmn%3E9%3C%2Fmn%3E%3Cmn%3E5%3C%2Fmn%3E%3Cmn%3E%EF%BC%9B%3C%2Fmn%3E%3Cmi%3ED%3C%2Fmi%3E%3Cmn%3E.%3C%2Fmn%3E%3Cmn%3E9%3C%2Fmn%3E%3Cmn%3E5%3C%2Fmn%3E%3Cmtext%3E%E2%A9%BD%3C%2Fmtext%3E%3Cmi%3Ex%3C%2Fmi%3E%3Cmtext%3E%E2%A9%BD%3C%2Fmtext%3E%3Cmn%3E1%3C%2Fmn%3E%3Cmn%3E0%3C%2Fmn%3E%3Cmn%3E0%3C%2Fmn%3E%3Cmn%3E%29%3C%2Fmn%3E%3C%2Fmath%3E)
![](http://tikupic.21cnjy.com/2023/09/15/16/06/16068a125ff6f47647459c4f1221f5b8_277x127.png)
其中,八年级20名学生的成绩是:80,81,82,82,84,85,86,87,89,90,90,91,94,96,96,96,96,96,99,100.
九年级20名学生的成绩在
组中的数据是:90,91,92,92,93,94.
八、九年级抽取的学生竞赛成绩统计表
年级 | 平均数 | 中位数 | 众数 | 方差 |
八年级 | 90 | 90 | b | 38.7 |
九年级 | 90 | c | 100 | 38.1 |
根据以上信息,解答下列问题: