In the previous question, suppose that the management decides to use a p chart for the analysis. As noted earlier, 10% of produced items are known to be nonconforming.

The firm analyzes a batch of production items for 6 weeks and computes the following percentages of nonconforming items.

Week Nonconforming Percentage

1........... 5.5%

2...........13.1%

3...........16.8%

4...........13.6%

5...........19.8%

6........... 2.0%

a. Suppose weekly batches consisted of 50 items.

Construct a p chart and determine if the machine needs adjustment in any of the weeks.

b. Suppose weekly batches consisted of 100 items.

Construct a p chart and determine if the machine needs adjustment in any of the weeks.