Sit-ups and the 40-yard dash Is there a relationship between how many sit-ups you can do and how fast you can run 40 yards? The EXCEL output shows the relationship between these variables for a study of female athletes to be discussed in Chapter 12.

a. The regression equation is yn = 6.71

- 0.024x. Find the predicted time in the 40-yard dash for a subject who can do (i) 10 sit-ups, (ii) 40 sit-ups. Based on these times, explain how to sketch the regression line over this scatterplot.

b. Interpret the y-intercept and slope of the equation in part

a, in the context of the number of sit-ups and time for the 40-yard dash.

c. Based on the slope in part

a, is the correlation positive or negative? Explain.

40-yd dash (sec.) 5.5 5 6.5 6 7 10 15 20 20 25 Sit-ups 30 35 40 Excel scatterplot of time to run 40-yard dash by number of sit-ups.