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扑扑扑 · 2020年07月16日

问一道题:NO.PZ2017092702000156

问题如下:

Using the information in the following table, the sample standard deviation for VWIGX is closest to:

选项:

A.

6.02%

B.

12.04%.

C.

24.54%

解释:

C is correct. The sample variance is defined as sum of the squared deviations from the sample mean divided by the sample size minus one, and the sample standard deviation equals the square root of the sample variance.

The sample variance is thus equals to 6.02. The square root of the sample variance is the sample standard deviation and equals to 24.54%.

A is incorrect because it is the sample variance for VWGIX, not its sample standard deviation.
B is incorrect because it represents the sum of the squared deviations from the mean, not the sample standard deviation.


请问这道题应该怎么算呢?我用计算器2nd 7 然后对应输入x的三个数值,然后2nd 8. 但算出来Sx是16.1602. 没有看到选项里的答案呀。请问是我哪里算错了吗?

2 个答案
已采纳答案

星星_品职助教 · 2020年07月16日

@扑扑扑

按 2nd+7后,可以直接先按2nd+左下角的CE/C键(即调用CLR WORK功能)进行清零以后再输入。就不会有这个问题了。建议每次用2nd+7这个功能的时候都先清零。

 

星星_品职助教 · 2020年07月16日

同学你好,

按键的逻辑是对的,但2nd+7,X输入三个值后。2nd+8的结果直接就是Sx=24.5316,即选择C选项