13-14. A statistics class is randomly divided into two groups. One uses only the textbook and the other uses the textbook and study guide. The final averages for the two groups are:

Textbook Only Textbook and Study Guide 77 63 75 84 79 82 74 91 94 96 87 72 93 98 82 85 Is there any evidence to indicate that those students who used the textbook and study guide earned higher course averages? Use α = 0.05 and perform a rank-sum test.