科教兴国,科普为先.某校组织七、八年级学生参加了“科普赋能,智行未来”科普知识竞赛.现从该校七、八年级学生中分别随机抽取了20名学生的竞赛成绩进行整理,描述和分析(成绩得分用
x表示,共分为五组:
![](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%3E0%3C%2Fmn%3E%3Cmo%3E%E2%89%A4%3C%2Fmo%3E%3Cmi%3Ex%3C%2Fmi%3E%3Cmo%3E%26lt%3B%3C%2Fmo%3E%3Cmn%3E7%3C%2Fmn%3E%3Cmn%3E0%3C%2Fmn%3E%3Cmtext%3E++%EF%BC%8C+%3C%2Fmtext%3E%3Cmi%3EB%3C%2Fmi%3E%3Cmn%3E.%3C%2Fmn%3E%3Cmn%3E7%3C%2Fmn%3E%3Cmn%3E0%3C%2Fmn%3E%3Cmo%3E%E2%89%A4%3C%2Fmo%3E%3Cmi%3Ex%3C%2Fmi%3E%3Cmo%3E%26lt%3B%3C%2Fmo%3E%3Cmn%3E8%3C%2Fmn%3E%3Cmn%3E0%3C%2Fmn%3E%3Cmtext%3E++%EF%BC%8C+%3C%2Fmtext%3E%3Cmi%3EC%3C%2Fmi%3E%3Cmn%3E.%3C%2Fmn%3E%3Cmn%3E8%3C%2Fmn%3E%3Cmn%3E0%3C%2Fmn%3E%3Cmo%3E%E2%89%A4%3C%2Fmo%3E%3Cmi%3Ex%3C%2Fmi%3E%3Cmo%3E%26lt%3B%3C%2Fmo%3E%3Cmn%3E9%3C%2Fmn%3E%3Cmn%3E0%3C%2Fmn%3E%3Cmtext%3E++%EF%BC%8C+%3C%2Fmtext%3E%3Cmi%3ED%3C%2Fmi%3E%3Cmn%3E.%3C%2Fmn%3E%3Cmn%3E9%3C%2Fmn%3E%3Cmn%3E0%3C%2Fmn%3E%3Cmo%3E%E2%89%A4%3C%2Fmo%3E%3Cmi%3Ex%3C%2Fmi%3E%3Cmo%3E%E2%89%A4%3C%2Fmo%3E%3Cmn%3E1%3C%2Fmn%3E%3Cmn%3E0%3C%2Fmn%3E%3Cmn%3E0%3C%2Fmn%3E%3Cmtext%3E%EF%BC%89%3C%2Fmtext%3E%3C%2Fmath%3E)
, 下面给出了部分信息:
七年级20名学生的成绩是:69,76,78,79,82,84,85,86,86,86,86,88,88,90,92,92,95,98,100,100.
八年级20名学生的成绩在C组中的数据是:83,85,85,86,87,89,89,89,89.
七、八两年级抽取的学生成绩数据统计表
班级 | 平均数 | 中位数 | 众数 | 满分率 |
七年级 | 87 | 86 | a | ![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmn%3E1%3C%2Fmn%3E%3Cmn%3E0%3C%2Fmn%3E%3Cmn%3E%25%3C%2Fmn%3E%3C%2Fmath%3E)
|
八年级 | 87 | b | 89 | ![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmn%3E1%3C%2Fmn%3E%3Cmn%3E5%3C%2Fmn%3E%3Cmn%3E%25%3C%2Fmn%3E%3C%2Fmath%3E)
|
八年级抽取的学生成绩扇形统计图
![](http://tikupic.21cnjy.com/2024/02/25/83/c4/83c41b4ffbd5f37ba5e3aecc8d05f82c_128x148.png)
根据以上信息,解答下列问题: