问题
单项选择题
When is the t- distribution the appropriate distribution to use The t -distribution is the appropriate distribution to use when constructing confidence intervals based on:（）
A. small samples from populations with known variance that are at least approximately normal.
B. large samples from populations with known variance that are nonnormal.
C. small samples from populations with unknown variance that are at least approximately normal.
答案
参考答案：C
解析：
The t- distribution is the appropriate distribution to use when constructing confidence intervals based on small samples from populations with unknown variance that are either normal or approximately normal.