When estimating a confidence interval for the difference bet

When estimating a confidence interval for the difference between 2 means using the method where sample variances are pooled, which of the following assumptions is not needed?

A) The populations are normally distributed.

B) The populations have equal variances.

C) The samples are independent.

D) The sample sizes are equal.

Solution

For estimating a confidence interval for the difference between 2 means using the method where sample variances are pooled, the assumption of normally distributed, independent and equal variances of samples are required. However, it is not necessary that the sample sizes are equal.

Answer D. The sample sizes are equal.