一个容量为20的样本数据分组后，组距与频数如下：(10,20),2；(20,30),3；(30,40),4；(40,50),5；(50,60),4，(60,70),2.则样本在区间(－∞，50)上的频_刷题宝

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一个容量为20的样本数据分组后，组距与频数如下：(10,20),2；(20,30),3；(30,40),4；(40,50),5；(50,60),4，(60,70),2.则样本在区间(－∞，50)上的频率是（）

A：0.20　　

B：0.25

C：0.50　　

D：0.70

上一题下一题 0.0难度选择题更新时间:2018-04-11 11:04:11

答案(点此获取答案解析）

D

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