In: Statistics and Probability
The data below represent the number of days absent, x, and the final grade, y, for a sample of college students at a large university. Complete parts (a) through (e) below.
0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
89.0 | 86.1 | 83.0 | 80.5 | 77.4 | 73.0 | 63.3 | 67.8 | 64.8 | 61.8 |
(a) Find the least-squares regression line treating the number of absences, x, as the explanatory variable and the final grade, y, as the response variable.
(b) Interpret the slope and y-intercept, if appropriate.
(c) Predict the final grade for a student who misses two class periods and compute the residual. Is the observed final grade above or below average for this number of absences?
(d) Draw the least-squares regression line on the scatter diagram of the data.
(e) Would it be reasonable to use the least-squares regression line to predict the final grade for a student who has missed 18 class periods? Why or why not?