medium · SAT Math

The scatterplot below shows, for 12 volunteers, the number of hours of sleep the night before a test (x, in hours) and the volunteer's score on a 100-point memory test (y, in points). The data points span x = 4 to x = 10 hours. Volunteer: Hours slept (x) | Test score (y, points) 1: 4 | 48 2: 5 | 58 3: 5 | 63 4: 6 | 60 5: 6 | 66 6: 7 | 76 7: 7 | 71 8: 8 | 74 9: 8 | 80 10: 9 | 86 11: 9 | 90 12: 10 | 87 The line of best fit for this data is y = 6.5x + 22, where y is the predicted memory-test score (points) for a volunteer who slept x hours. Volunteer 7 slept 7 hours and scored 71 points on the test. What is the residual for Volunteer 7's data point?

1. -3.5
2. 3.5
3. 67.5
4. 71

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