Historically,the average proportion of defective bars has been 0.015.Samples will be of 100 bars each.Construct a p-chart using z = 3.Suppose a sample had 0.07 defective.What would you do?
A) Nothing; it is just random variation.
B) Look for assignable causes.
C) Change z to 2 and take another sample.
D) Change z to 4 and continue sampling.

Question

Quizplus · Accepted Answer

When the sample proportion exceeds the control limits, it suggests a potential problem or assignable cause. In this case, the sample proportion is 0.07, which is higher than the upper control limit of the p-chart. Therefore, the best choice would be to look for assignable causes. Option A is incorrect because a sample proportion of 0.07 is significantly higher than the historical average and is unlikely to be attributed to random variation. Option C and D are irrelevant since changing the value of z or continuing to sample would not address the underlying assignable causes.

Historically,the Average Proportion of Defective Bars Has Been 0