Two independent samples of sizes 20 and 25 are randomly selected from two normal populations with equal variances.In order to test the difference between the population means,the test statistic is:
A) a standard normal random variable
B) approximately standard normal random variable
C) t-distributed with 45 degrees of freedom
D) t-distributed with 43 degrees of freedom

Question

Quizplus · Accepted Answer

When testing the difference between two means from independent samples with equal variances, the test statistic follows a t-distribution with degrees of freedom calculated as (n1 + n2 - 2), which in this case is (20 + 25 - 2) = 43.

Two Independent Samples of Sizes 20 and 25 Are Randomly