Suppose that 8% of all cars produced at Plant A have a certain defect, and 5% of all cars produced at Plant B have this defect. A quality control manager takes separate random samples of 150 cars from each plant. The manager will then look at the difference (A-B) between the proportions of cars with the defect in each sample.
What will be the shape of the sampling distribution of the difference in sample proportions, and why?
Choose 1 answer:
A. Approximately normal, because we expect 12 defective and 138 defect-free cars from Plant A, and 15 and 135 from Plant B, and all of these counts are at least 10.
B. Approximately normal, because we expect 16 defective and 134 defect-free cars from Plant A, and 10 and 140 from Plant B, and all of these counts are at least 10.
C. Not normal, because we expect fewer than 10 defective cars in Plant A.
D. Not normal, because we expect fewer than 10 defective cars in Plant B.