单选题

An analyst conducts a two-tailed test to determine whether differences between the means of two populations exist:H₀ :μ₁ -μ₂=0 versus H₂ :μ₁ -μ₂ ≠ 0. Assume that the populations are independent, normally distributed, and have unequal and unknown variances.The critical value with 50 degrees of freedom is 2.126. The computed test statistic is t=1.753. Using a significance level of x= 0.05, which of the following statements is TRUE?（）

A、 Use a t-test to reject the null hypothesis and accept the alternative hypothesis.
B、 Use a t-test to accept the null hypothesis and reject the alternative hypothesis.
C、 Use a z-test to reject the null hypothesis and accept the alternative hypothesis.

【正确答案】 B

【答案解析】

The appropriate test is a t-test concerning differences between means.Because the critical value is greater than the computed t-value, the null hypothesis cannot be rejected at the 0.05 level of significance.