Question 4 (15 points) A sports psychologist wanted to find out whether there is a relationship between drinking coffee and speed in running a 5 k run. He recorded the time (in minutes) of 5 coffee drinkers competing in the marathon as follows: 27, 25, 23, 24, 26, and 5 non- coffee drinkers also competing in the same marathon as follows: 28, 24, 13, 21, 20. Convert these data into a form suitable for the point-biserial correlation, and assign a score of 0 to the non-coffee drinkers and a 1 to the coffee drinkers. A) Compute the point biserial correlation (13 pts), and B) compute the coefficient of determination (r2) and describe how much of the variability in marathon speed is determined by its association with drinking coffee. (2 pts)