Answer:
Step-by-step explanation:
Independently selected samples measures scores on the same variable but for two different groups of cases while Paired-samples measures scores on two different variables but for the same group of cases.
In case study 1, the sample is independently selected; a random sample of 100 science majors and a random sample of 75 liberal arts majors are selected: two different group of cases and just one variable, to compare the mean number of hours.
In case study 2, the samples are paired, a random sample of science majors is selected. Each student in this sample is asked for two data values: a group of case but two different variables; how much money they spent on textbooks in the spring semester and how much money they spent on textbooks in the fall semester were measured.
In case study 3, the samples were independently selected. Two different group of cases; a random sample of science majors is selected. A separate random sample of the same size is selected from the population of liberal arts majors were measured for just one variable the mean amount of time spend in campus.