2017年高考特别强调了要增加对数学文化的考查,为此某校高三年级特命制了一套与数学文化有关的专题训练卷
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmo+stretchy%3D%22false%22%3E%28%3C%2Fmo%3E%3C%2Fmath%3E)
文、理科试卷满分均为100分
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmo+stretchy%3D%22false%22%3E%29%3C%2Fmo%3E%3C%2Fmath%3E)
, 并对整个高三年级的学生进行了测试,现从这些学生中随机抽取了50名学生的成绩,按照成绩为
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmrow%3E%3Cmo%3E%5B%3C%2Fmo%3E%3Cmrow%3E%3Cmn%3E50%3C%2Fmn%3E%3Cmtext%3E++%EF%BC%8C+%3C%2Fmtext%3E%3Cmn%3E60%3C%2Fmn%3E%3C%2Fmrow%3E%3Cmo%3E%29%3C%2Fmo%3E%3C%2Fmrow%3E%3Cmtext%3E++%EF%BC%8C+%3C%2Fmtext%3E%3Cmrow%3E%3Cmo%3E%5B%3C%2Fmo%3E%3Cmrow%3E%3Cmn%3E60%3C%2Fmn%3E%3Cmtext%3E++%EF%BC%8C+%3C%2Fmtext%3E%3Cmn%3E70%3C%2Fmn%3E%3C%2Fmrow%3E%3Cmo%3E%29%3C%2Fmo%3E%3C%2Fmrow%3E%3Cmo%3E++%EF%BC%8C+%3C%2Fmo%3E%3Cmo%3E%E2%80%A6%3C%2Fmo%3E%3Cmo%3E++%EF%BC%8C+%3C%2Fmo%3E%3Cmrow%3E%3Cmo%3E%5B%3C%2Fmo%3E%3Cmrow%3E%3Cmn%3E90%3C%2Fmn%3E%3Cmtext%3E++%EF%BC%8C+%3C%2Fmtext%3E%3Cmn%3E100%3C%2Fmn%3E%3C%2Fmrow%3E%3Cmo%3E%5D%3C%2Fmo%3E%3C%2Fmrow%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
分成了5组,制成了如图所示的频率分布直方图
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmo+stretchy%3D%22false%22%3E%28%3C%2Fmo%3E%3C%2Fmath%3E)
假定每名学生的成绩均不低于50分
![](http://tikupic.21cnjy.com/2024/01/16/96/fb/96fb22da3e673fd6436e4cf2bc5b6151_427x306.jpg)
(Ⅰ)求频率分布直方图中的
的值,并估计所抽取的50名学生成绩的中位数
用分数表示
;
(Ⅱ)若利用分层抽样的方法从样本中成绩不低于70分的三组学生中抽取6人,再从这6人中随机抽取2人参加这次考试的考后分析会,试求
组中至少有1人被抽到的概率.