单选题

Using the above data, an analyst is trying to test the null hypothesis that the population variances are equal against the alternative hypothesis that the variances are not equalat the 5% level of significance.
Table of the F-Distribution
Panel A: Critical values for right-hand tail areas equal to 0.05

Panel B: Critical values for right-hand tail areas equal to 0.025

A、 6.39 and reject the null.
B、 7.15 and do not reject the null.
C、 9.60 and do not reject the null.

【正确答案】 C

【答案解析】

C is correct. The test statistic is the ratio of the variances, with the larger variance in the numerator. Here, the test statistic is 28 + 4 = 7. The degrees of freedom are 4 by 4. Because it is a two-tailed test, the correct critical value at α = 5% is 9.60. And because the test statistic is less than the critical value, we cannot reject the null hypothesis. We thus accept the null hypothesis.