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Nan🌞 · 2021年09月21日

解析中的方法看不懂,有没有直接了当的方法?我算出来是33.3%

NO.PZ2021061603000010

问题如下:

An analyst is using the data in the following exhibit to prepare a statistical report.


The cumulative relative frequency for the bin -1.71% ≤x< 2.03% is closest to:

选项:

A. 0.250

B. 0.333

C. 0.583

解释:

C is correct. The cumulative relative frequency of a bin identifies the fraction of observations that are less than the upper limit of the given bin. It is determined by summing the relative frequencies from the lowest bin up to and including the given bin. The following exhibit shows the relative frequencies for all the bins of the data from the previous exhibit:


The bin-1.71% ≤x < 2.03% has a cumulative relative frequency of 0.583.

题目中不是求-1.71到2.03之间的累积占比吗?为什么要把小于-1.71的数据也算进去?
1 个答案

星星_品职助教 · 2021年09月21日

同学你好,

题目要求计算the cumulative relative frequency ”for the interval -1.71% ≤ x < 2.03%.

cumulative relative frequency的定义为:For data grouped into intervals, the fraction of total observations that are less than the value of the UPPER limit of a stated interval.

根据定义可以看出,求the cumulative relative frequency 就是求低于区间上限的所有的数字(observations)的数量占总数字数量的比例,在本题中,区间的上限数字是2.03%

所以在表格中找到所有小于2.03%的数字,发现有7个,总数字一共12个,这个时候cumulative relative frequency 就是7/12=0.5833