Independent samples are obtained from two normal populations with unknown but equal standard deviations (variances) in order to construct a hypothesis test for the difference between the population means.If the first sample contains 20 items and the second sample contains 25 items, the correct form to use for the sampling distribution is the
A)normal distribution
B)t distribution with 43 degrees of freedom
C)t distribution with 45 degrees of freedom
D)F distribution with 20 and 25 degrees of freedom
E)none of the above

Question

Quizplus · Accepted Answer

When comparing means from two independent samples with unknown but equal variances, the appropriate distribution to use is the t distribution. The degrees of freedom (df) for this test are calculated using the formula df = n1 + n2 - 2, where n1 and n2 are the sample sizes. Here, df = 20 + 25 - 2 = 43.

Independent Samples Are Obtained from Two Normal Populations with Unknown