Retail chain Kroger has more than locations and is the largest supermarket in the United States based on revenue. Kroger has invested heavily in data, technology, and analytics. Feeding predictive models with data from an infrared sensor system called QueVision to anticipate when shoppers will reach the checkout counters, Kroger is able to alert workers to open more checkout lines as needed. This has allowed Kroger to lower its average checkout time from four minutes to less than seconds (Retail Touchpoints). Each observation gives the arrival time (measured in minutes before p. m.) and the shopping time (measured in minutes). Arrival Time (Minutes Before 6:00 p. m.) Shopping Time (Minutes)
59 24
22 19
58 25
84 29
53 40
97 45
38 32
12 25
0 11
132 54

Required:
a. Develop a scatter diagram for arrival time as the independent variable.
b. What does the scatter diagram developed in part (a) indicate about the relationship between the two variables?
c. Does there appear to be an outlier or influential observation?
d. Using the entire data set, develop the estimated regression equation that can be used to predict the shopping time given the arrival time. (Let x = arrival time (in minutes before 6:00 p. m.), and let y = shopping time (in minutes). Round your numerical values to four decimal places.)