这题直观上能理解，公式上能不能有解释，另A错在哪里啊，A不是在Z检验的分母上么，越大，求出来的数值越小啊
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No.PZ2018062016000115 (选择题)
来源: 品职出题
If analyst want to decrease the width of the confidence interval, which of the following statement should be selected.
您的回答, 正确答案是: B
A
不正确increase sample variance
B
increase number of observations
C
increase confidence level
数据统计(全部)
做对次数: 1161
做错次数: 397
正确率: 74.52%
数据统计(个人)
做对次数: 0
做错次数: 1
正确率: 0.00%
解析
B is correct, if number of observation become larger, sample variance is smaller, the width of confidence interval become smaller.
观察的次数越多，样本方差越小，置信区间的宽度越小。
