The accompanying data are a subset of data from the report “Great Jobs, Great Lives” (Gallup-PurdueIndex 2015 Report, gallup.com/reports/197144 /gallup-purdue index-report-2015.aspx). The values are approximate values read from a scatterplot.

Students at a number of universities were asked if they agreed that their education was worth the cost. One variable in the table is the percentage of students at the university who responded strongly agree. The other variable in the table is the U.S. News and World Report ranking of the university.

Ranking .............. Percentage of Alumni Who Strongly Agree
28 ............................................................... 53
29 ............................................................... 58
30 ............................................................... 62
37 ............................................................... 55
45 ............................................................... 54
47 ............................................................... 62

52 ............................................................... 55
54 ............................................................... 62
57 ............................................................... 70
60 ............................................................... 58
65 ............................................................... 66
66 ............................................................... 55
72 ............................................................... 65
75 ............................................................... 57
82 ............................................................... 67
88 ............................................................... 59
98 ............................................................... 75

a. Find the equation of the least-squares line that would allow you to predict the percentage of alumni who would strongly agree that their education was worth the cost, using ranking as the independent variable.

b. Predict the percentage of alumni who would strongly agree that their education was worth the cost for a university with a ranking of 50.

c. Explain why it would not be a good idea to use the least-squares line to predict the percentage of alumni who would strongly agree that their education was worth the cost for a university that had a ranking of 10.