设X1，X2，…，Xn是来自总体N(μ，σ2)的简单随机样本，
为样本的均值，记
则下列服从自由度为n-1的t分布的随机变量是
参考答案：B
解析：
[分析]： 由正态总体抽样分布与t分布典型模式知，服从t(n-1)的随机变量仅能在含有[*]的选项(A)、(B)中考虑，这是因为
[*]
又由[*]
即知正确选项应该是(B)．事实上，由于总体X～N(μ，σ2)，故
[*]
所以
[*]
[*]
| 阅读下面短文，在表格内的空白处填入合适的答案 (每格词数不限)。 | ||||||
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Title: Sending E-cards on the Internet
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