为培养学生良好的运动习惯和运动能力,我校本学期开展了“趣味运动会”和“冬季长跑”等体育活动.为了解九年级学生的长跑水平,我校对全体九年级同学进行了长跑测试,体育组陈老师随机抽取20名男生和20名女生的测试成绩(满分100)进行整理和分析(成绩共分成五组:A.
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmn%3E50%3C%2Fmn%3E%3Cmo%3E%E2%89%A4%3C%2Fmo%3E%3Cmi%3Ex%3C%2Fmi%3E%3Cmo%3E%26lt%3B%3C%2Fmo%3E%3Cmn%3E60%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
,B.
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmn%3E60%3C%2Fmn%3E%3Cmo%3E%E2%89%A4%3C%2Fmo%3E%3Cmi%3Ex%3C%2Fmi%3E%3Cmo%3E%26lt%3B%3C%2Fmo%3E%3Cmn%3E70%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
,C.
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmn%3E70%3C%2Fmn%3E%3Cmo%3E%E2%89%A4%3C%2Fmo%3E%3Cmi%3Ex%3C%2Fmi%3E%3Cmo%3E%26lt%3B%3C%2Fmo%3E%3Cmn%3E80%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
,D.
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmn%3E80%3C%2Fmn%3E%3Cmo%3E%E2%89%A4%3C%2Fmo%3E%3Cmi%3Ex%3C%2Fmi%3E%3Cmo%3E%26lt%3B%3C%2Fmo%3E%3Cmn%3E90%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
,E.
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmn%3E90%3C%2Fmn%3E%3Cmo%3E%E2%89%A4%3C%2Fmo%3E%3Cmi%3Ex%3C%2Fmi%3E%3Cmo%3E%26lt%3B%3C%2Fmo%3E%3Cmn%3E100%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
),绘制了不完整的统计图表:
收集、整理数据
20名男生的长跑成绩分别为:
76,77,95,88,50,89,89,97,99,93,97,89,65,87,68,89,78,88,98,88.
女生长跑成绩在C组和D组的分别为:
73,74,74.74,74,76,83,88,89.
![](http://tikupic.21cnjy.com/2023/06/25/3b/74/3b74cf8e5085092411625bed12ffbba6_m_268x246.png)
分析数据:两组样本数据的平均数、中位数和众数如表所示:
长跑成绩 | 平均数 | 中位数 | 众数 |
男生 | 85 | 88.5 | b |
女生 | 81.8 | a | 74 |
请根据以上信息,回答下列问题;