The same excavator part is being manufactured on two separate lines at Ace #1 Machinery Co. The production manager is comparing the reliability of the manufacturing process and had gathered some data on the number of defective parts created by each line.

Can the manager say that there is a difference in the proportion of defective parts created by Line 1 vs. Line 2? Use a level of significance of 0.05. [9 marks]

Number of defective parts

Total number of parts tested

Line 1

50

275

Line 2

32

215