In a large class, 13 students required a makeup examination. The instructor gave the same test to everyone but because of circumstances, he could find a quiet environment for only 5 of the students. The other 8 had to take their test in a noisy environment. Assignment to testing environment can be considered random. The scores of the two groups were
Noisy environment: 55 38 46 63 35 61 56 47
Quiet environment: 62 56 47 65 59
Is the difference in performance significant according to a two-tailed test using a = .05? Use the Mann-Whitney U test to solve the problem. Interpret the outcome using appropriate descriptive statistics.