Opinions about whether caffeine enhances test performance differ. You design a study to test the impact of drinks with different caffeine contents on students' test-taking abilities. You choose 21 students at random from your introductory psychology course to participate in your study. You randomly assign each student to one of three drinks, each with a different caffeine concentration, such that there are seven students assigned to each drink. You then give each of them a plain capsule containing the precise quantity of caffeine that would be consumed in their designated drink and have them take an arithmetic test 15 minutes later. The students receive the following arithmetic test scores: Cola Black Tea Coffee Caffeine Content (mg/oz) 2.9 5.9 13.4 85 85 92 EX = 147,641 86 89 87 G-1,755 82 82 80 N-21 75 75 89 k=3 66 88 96 78 76 83 87 82 92 T-559 T-577 T-619 SS-338.86 SS-177.71 SS-185.71 1-7 3-7 1=7 M. 79.8571 M. 82.4286 M. 88.4286