To ensure that a manufacturing process is under control,40 samples of size 900 were drawn,and the number of defectives in each sample was counted.The mean of the sample proportion was .025.Then,the lower and upper control limits for the p chart are .0094 and .0406,respectively.

Question

Quizplus · Accepted Answer

The given information indicates that a p chart is being used to monitor the proportion of defectives in the process. The control limits for a p chart are calculated as:

Lower control limit (LCL) = p̂ - 3 * sqrt(p̂(1 - p̂) / n)
Upper control limit (UCL) = p̂ + 3 * sqrt(p̂(1 - p̂) / n)

where p̂ is the average sample proportion, n is the sample size, and sqrt is the square root function.

Substituting the given values, we get:

LCL = 0.025 - 3 * sqrt(0.025 * (1 - 0.025) / 900) = 0.0094
UCL = 0.025 + 3 * sqrt(0.025 * (1 - 0.025) / 900) = 0.0406

Therefore, the statement is true.

To Ensure That a Manufacturing Process Is Under Control,40 Samples