A group of students in a class decided to try a new homework strategy. The test was multiple-choice, and each question had five possible response options. They have now received their grades (in percent %) and want to know whether, on average, they did better or worse at guessing the answers than would be predicted by guessing totally randomly between all five options for each question. Their grades are below. On average, did the class score better, worse, or neither, compared to pure chance? (You may assume that there were many questions on the test that they took)

Student

Test grade (%)

Arnold 28

Carlos 27

Keesha 14

Phoebe 18

Tim 18

Wanda 19

Ralphie 12

Liz 19

George 23

Janet 25

a) Conduct the appropriate test to answer this research question, alpha=.05, two-tailed. Please be sure show your work and label each step of the process. (10 points)

b) Ralphie decides to use a 1-tailed test instead because he is certain that they will do BETTER than expected. What is his conclusion? (1 point)

c) Tim thought that maybe they should look at practical significance. Choose one method and perform the appropriate calculation. Interpret the result in 1 sentence. (2 points)