In a manufacturing process the assembly line speed (feet per minute) with thought to affect the number of defective parts found during the inspection process. To test this theory, managers devised a situation in which the same batch of pots was inspected visually at a variety of line speeds. They collected the following data. Line Speed Number of defective parts found
20 21
20 19
40 15
30 16
60 14
40 17

Required:
a. Develop the estimated regression equation that relates line speed to the number of defective parts found.
b. At α= 0.05 level of significance, determine whether line speed and number of defective parts found are related.
c. Did the estimated regression equation provide a good fit to the data?
d. Develop a 95% confidence interval to predict the mean number of defective parts for a line speed of 50 feet per minute.