A history instructor wondered about the effectiveness of graded quizzes over material that students were supposed to read prior to class. For one of his sections, quizzes were administered and graded. For another section, the same quizzes were administered but instead of counting toward their grade, students simply used them as practice for exams. Final grade distributions for both sections are shown in the table below. Is there a relationship between final grades and whether quizzes are graded or used for practice? Conduct a chi-square test of independence using a = .05.