In a left-tailed test comparing two means with variances unknown but assumed to be equal, the sample sizes were n₁ = 8 and n₂ = 12. At α = .05, the critical value would be: A)-1.960 B)-2.101 C)-1.734 D)-1.645

Question

Quizplus · Accepted Answer

For a left-tailed test comparing two means with unknown but assumed equal variances, the degrees of freedom (df) are calculated using the formula for pooled variance. Given the sample sizes n1 = 8 and n2 = 12, the total df = n1 + n2 - 2 = 8 + 12 - 2 = 18. Looking up the critical value for α = .05 in a t-distribution table with 18 degrees of freedom, the closest value is -1.734, which corresponds to option C.

In a Left-Tailed Test Comparing Two Means with Variances Unknown