Please select the correct answer and explain briefly why:
1. In order to test the effectiveness of a drug called XZR designed to reduce cholesterol levels, 20 heart patients' cholesterol levels are measured before they are given the drug. The same 20 patients use XZR for two continuous months. After two months of continuous use the 20 patients' cholesterol levels are measured again. The comparison of cholesterol levels before vs. after administering the drug is an example of testing the difference between:
A. Two means from independent populations
B. Matched pairs from two dependent populations
C. Two means from independent populations with unknown variances
D. Two means from independent populations with equal variances
2. If the t statistic (critical value) is used in lieu of the Z statistic when comparing two means from independent populations using small samples, the probability of rejecting the null hypothesis __________.
C. Remains the same
D. Depends on whether the population is normal
The solution provides answers to multiple choice questions on hypothesis testing. Short explanation of the answer is also included.