3.8 The figure for this exercise is a scatterplot of y 5 pulse rate after marching in place for 1 minute versus x 5 resting pulse rate measured before marching in place. (The data are in the pulsemarch dataset on the companion website.)

105 100 95 90 85 80 75 70 65 60 Pulse after marching Pulse before marching 45 50 55 60 65 70 75 80 85 90 95

a. Does the plot show a positive association, a negative association, or no association between the two variables?

Explain.

b. Explain whether you think the pattern of the plot is linear or curvilinear.

c. According to MayoClinic.com normal resting pulse rates for adults range from about 60 to 100, and for wellconditioned athletes they range from about 40 to 60. Using this information, explain whether there are any outliers in the scatterplot that are obvious mistakes. If there are outliers, describe where they are located on the plot.