The following are the scores in the midterm and the final exam in a graduate physics co student midterm (X) final (Y) 1 87 88 2 72 97 3 75 70 4 84 98 UI 80 80 79 94 J 82 82 8 88 83 9 85 85 10 91 89 11 83 93 Use the sign test to test whether the student performance improved. The number of negative signs for (x-y), n , equals to v [ Select ] 3 6 none of these 4 5 Previous 7