=+17. Nine students currently taking introductory statistics are randomly selected, and both the first midterm exam score (x) and the second midterm score

(y) are determined. Three of the students have the class at 8 a.m., another three have it at noon, and the remaining three have a night class. The resulting (x, y) pairs are as follows:

8 a.m.: (70, 60) (72, 83) (94, 85)

Noon: (80, 72) (60, 74) (55, 58)

Night: (45, 63) (50, 40) (35, 54)