Exam 10: Quality Control

Studies on a bottle-filling machine indicate that it fills bottles to a mean of 16 ounces with a standard deviation of 0.10 ounces. What is the process specification, assuming the C_pk index of 1?

A p-chart is used to monitor the fraction of defectives in the output of a process.

Process capability compares process variability to the tolerances.

C_pk is useful even when the process is not centered.

A quality analyst wants to construct a sample mean chart for controlling a packaging process. He knows from past experience that whenever this process is under control, package weight is normally distributed with a mean of 20 ounces and a standard deviation of two ounces. Each day last week, he randomly selected four packages and weighed each: Weight (ounces) Day Monday 23 22 23 24 Tuesday 23 21 19 21 Wednesday 20 19 20 21 Thursday 18 19 20 19 Friday 18 20 22 20 If he uses upper and lower control limits of 22 and 18 ounces, on what day(s), if any, does this process appear to be out of control?

A stent for use in coronary surgery requires a special coating. Specifications for this coating call for it to be at least 0.05 millimeters but no more than 0.15 millimeters. Suppose the criterion for evaluating this process is that the appropriate capability index must be at least 1.3. With a long-run process mean of 0.09 and a standard deviation of 0.015, is this process capable?

A point which is outside of the lower control limit on an R-chart:

Which of the following is not a step in the quality control process?

Given the following process control data for a normally distributed quality variable (three samples of size four each): Measurements Machine \#1 15 14 15 12 \#2 18 16 20 16 \#3 16 17 16 17 If this process is known to have a mean of 15 and a standard deviation of 3, what is the mean of the sampling distribution of sample means for whenever this process is under control? The standard deviation?

High-cost, low-volume items often require careful inspection since we make them so infrequently.

An R value of zero (on a range chart) means that the process must be in control since all sample values are equal.

When a process is in control, it results in there being, on average, 16 defects per unit of output. c-chart limits of 8 and 24 would lead to a _______ percent chance of a Type I error.

A c-chart is used to monitor the total number of defectives in the output of a process.

Attributes need to be measured, whereas variable data can be counted.

An analyst has gathered data and counted the number of runs with respect to the median. There were 60 observations and 22 runs. What can the analyst conclude given this information?

The greater the volume of the process being targeted for inspection, the more attractive __________ inspection is.

Inspection is a(n):

A design engineer wants to construct a sample mean chart for controlling the service life of a halogen headlamp his company produces. He knows from numerous previous samples that this service life is normally distributed with a mean of 500 hours and a standard deviation of 20 hours. On three recent production batches, he tested service life on random samples of four headlamps, with these results: Service Life (hours) Sample 1 495 500 505 500 2 525 515 505 515 3 470 480 460 470 What is the mean of the sampling distribution of sample means when service life is in control?

Attribute data are counted, variable data are measured.

Larger samples will require wider x-bar control limits because there is more data.