A Six Sigma team is reviewing the following data from a 2-sample t-test on Unit...

The correct answer is C. Reject the null hypothesis that the means are equal . The output shown is from a 2-sample t-test with unequal variances , which the CSSBB material identifies as the correct test when comparing two sample means and the variances are unknown and not assumed equal . In that case, the hypotheses are H0: μ1 = μ2 and H1: μ1 ≠ μ2 .

Here, the results show α = 0.05 , t = 8.14 , and p-value = 0.000 . CSSBB guidance states that when the p-value is below the selected significance level, the null hypothesis should be rejected . Also, the reported 95% confidence interval for the difference = (3.097, 5.289) does not include zero , which independently supports the conclusion that the two means are significantly different. Because the test shown is about means , not a formal test of equal variances, conclusions about variances should not be drawn from this output. Therefore, the proper conclusion is to reject the null hypothesis that the means are equal .