A researcher wanted to test the relationship between reaction time and time of day. She recruited 30 students and gave them a reaction time test in the morning and then the same test in the afternoon. The results of the test were classified as either "pass" or "fail". She found that in the morning 10 passed and 20 failed, and in the afternoon 15 passed and 15 failed. Can she use a chi square test of independence to see if there is a relationship between test performance and the time of day