题干

给出以下四个说法:

①绘制频率分布直方图时,各小长方形的面积等于相应各组的组距;

②在刻画回归模型的拟合效果时,相关指数R2的值越大,说明拟合的效果越好;

③设随机变量ξ服从正态分布N(4,22),则p(ξ>4)=

1
2

④对分类变量X与Y,若它们的随机变量K2的观测值k越小,则判断“X与Y有关系”的把握程度越大.

其中正确的说法是(   )

A:①④

B:②③

C:①③

D:②④

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答案(点此获取答案解析)

B

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