题目
When will we use a t-test instead of using z-test:
选项
A.The sample size is small.
B.The sample size is big.
C.The variance of the population is known.
D.The standard deviation is larger than the mean.
答案
A
解析
A t-test is used whenthe sample size is small and the variance of the population is unknown.当样本量较小且总体方差未知时，使用t检验。