The supervisor of a manufacturing process believed that assembly-line speed (in feet/minute) affected the number of defective parts found during on-line inspection. To test this theory, management had the same batch of parts inspected visually at a variety of line speeds. The following data were collected:

Number of

Line Speed Defective Parts Found

20 ..............21

20 ..............19

40 ..............15

30 ..............16

60 ..............14

40 ..............17

a. Develop the estimated regression equation that relates line speed to the number of defective parts found.

b. Use the equation developed in part (a) to forecast the number of defective parts found for a line speed of 50 feet per minute.