The owner of a test prep company was interested in whether students who took the company’s face to face test prep class did better on the GRE (a standardized test required for admission to many graduate programs) than students who followed the test prep company’s live online program. The live online test prep class met in an online classroom with live video instruction for the same number of hours as the face to face class. In which situation could the test prep company use the two-sample t-test for comparing two population means?
A) The students take part of their GRE test prep course online and the remaining part in the face to face method. The test prep company asks the students which they liked better. The company wants to determine if the majority prefer the online class.
B) The test prep company gives each student a pretest. Then each student completes the live online test prep class. Afterwards, each student takes a posttest. The test prep company wants to compare the pretest and posttest GRE scores for each student to see whether the data will show an improvement.
C) The test prep company randomly divides the students into two groups. One of the groups receives the face to face test prep class and the other group receives the live online test prep class. After completing their test prep course, each student takes the GRE and the test prep company compares the test scores of the two groups.