TABLE 10-5
To test the effectiveness of a business school preparation course, 8 students took a general business test before and after the course. The results are given below.
Exam Score Exam Score
Student Before Course (1) After Course (2)
1 530 670
2 690 770
3 910 1,000
4 700 710
5 450 550
6 820 870
7 820 770
8 630 610
-Referring to Table 10-5, the value of the sample mean difference is ________ if the difference scores reflect the results of the exam after the course minus the results of the exam before the course.
A) 0
B) 50
C) 68
D) 400

Question

Quizplus · Accepted Answer

The sample mean difference is calculated by taking the average of the differences between the after and before scores for all students. The differences are: 140, 80, 90, 10, 100, 50, -50, -20. The mean of these differences is 50.

TABLE 10-5 To Test the Effectiveness of a Business School Preparation Course