Do students who are members of fraternities or sororities have gpas different from the student body as a whole? a random sample of 123 "greeks" has been selected from the student body of a large university. the gpa for the student body as a whole is 2.59 and the mean for the sample is 2.47 with a standard deviation of 0.34. is the difference statistically significant? follow the five-step model and state all important decisions. make sure that you interpret the results in terms of the original research question.