Researchers measured the blood pressures of 22 students in two situations: when the students were relaxed and when the students were taking an important examination. The table lists the systolic and diastolic pressures for each student in each situation.40

(a) Compute the change in systolic pressure by subtracting systolic pressure when relaxed from systolic pressure during the exam; call this variable X.
(b) Repeat part (a) for diastolic pressure. Call the resulting variable Y.
(c) Make a scatterplot of Y versus X and fit a regression line to the data.
(d) Make a residual plot from the regression in part (c).
(e) Note the outlier in the residual plot [and on the scatterplot from part (c)]. Delete the outlier from the data set. Then repeat parts (c) and (d).
(f) What is the fitted regression model (after the outlier has been removed)?

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During exanm Relaxed Systolic Diastolic Systolic Diastolic pressure pressure (mm Hg) (mm Hg)(mm Hg) (mm Hg pressure pressurye 110 132 124 110 110 125 105 120 125 135 105 110 110 110 130 130 130 120 70 170 110 100 120 110 110 110 70 100 120 105 110 120 95 110 100 95 75 120 120 120 65 70