A mathematical placement test is given to all entering freshmen at a small college. A student who receives grades below 35 is denied admission to the regular mathematics course and placed in a remedial class. The placement test scores and the final grades for 20 students who took the regular courses were recorded as follows.

Placement Test (X) Course Grade (Y)
50                                    53
35                                    41
35                                    61
40                                    56
55                                    68
65                                    36
35                                    11
60                                    70
90                                    79
35                                    59
90                                    54
80                                    91
60                                    48
60                                    71
60                                    71
40                                    47
55                                    53
50                                    68
65                                    57
50                                    79