OSU-Tulsa Dursun Delen Ch. 10

I and III

Acceptance sampling, when it is used, is used: (I) before production. (II) during production. (III) after production. I only I and III only I and II only II and III only I, II, and III

False

T/F Concluding that a process is out of control when it is not is known as a Type I error.

True

T/F Control limits tend to be wider for more variable processes.

False

T/F Cpk is useful even when the process is not centered.

False

T/F Low-cost, high-volume items often require more intensive inspection than other types of items.

True

T/F Process capability compares process variability to the tolerances.

False

T/F Statistical process control is the measurement of rejects in the final product.

True

T/F The amount of inspection needed is governed by the costs of inspection and the expected costs of passing defective items.

False

T/F The optimum level of inspection occurs when we catch at least 98.6 percent of the defects.

False

T/F The output of a process may not conform to specifications even though the process may be statistically "in control."

True

T/F The output of a process may not conform to specifications even though the process may be statistically "in control."

False

T/F The process capability index (indicated by Cpk) can be used only when the process is centered.

True

T/F The sampling distribution can be assumed to be approximately normal even when the underlying process distribution is not normally distributed.

True

T/F Tolerances represent the control limits we use on the charts.

True

T/F If a point on a control chart falls outside one of the control limits, this suggests that the process output is nonrandom and should be investigated.

variability

The range chart (R-chart) is most likely to detect a change in: proportion. mean. number defective. variability. sample size.

1.67

The specifications for a product are 6 mm ± 0.1 mm. The process is known to operate at a mean of 6.05 with a standard deviation of 0.01 mm. What is the Cpk for this process? 3.33 1.67 5.00 2.50 1.33

False

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

500 hours

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: Sample: Service Life: 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? 250 hours 470 hours 495 hours 500 hours 515 hours

c-charts

A process results in a few defects occurring in each unit of output. Long-run, these defects should be monitored with: p-charts. c-charts. x-bar charts. R-charts. o-charts.

23.16 and 16.84

A quality analyst wants to construct a control chart for determining whether three machines, all producing the same product, are under control with regard to a particular quality variable. Accordingly, he sampled four units of output from each machine, with the following results: Machine: Measurements: 1 17 15 15 17 2 16 25 18 25 3 23 24 23 22 What are the x-bar chart three-sigma upper and lower control limits? 22 and 18 23.29 and 16.71 23.5 and 16.5 23.16 and 16.84 24 and 16

1 ounce

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: Day: Weight (ounces) : 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 What is the standard deviation of the sampling distribution of sample means for whenever this process is under control? 0.1 ounces 0.4 ounces 0.5 ounces 1 ounce 2 ounces

x-bar chart

A shift in the process mean for a measured characteristic would most likely be detected by a: p-chart. x-bar chart. c-chart. R-chart. s-chart.

control

A time-ordered plot of sample statistics is called a(n) ______ chart. statistical inspection control simo limit

I and II

If a process is performing as it should, it is still possible to obtain observations which are outside of which limits? (I) tolerances (II) control limits (III) process variability I II I and II II and III I, II, and III

True

T/F Attribute data are counted, variable data are measured.

E.) lower spec = 14.3 ounces and upper spec = 17.7 ounces

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 Cpk index of 1? A.) lower spec = 0.1 ounces and upper spec = 1 ounce B.) lower spec = 8.7 ounces and upper spec = 12.5 ounces C.) lower spec = 12.0 ounces and upper spec = 21.4 ounces D.) lower spec = 15.7 ounces and upper spec = 16.3 ounces E.) lower spec = 14.3 ounces and upper spec = 17.7 ounces

True

T/F A c-chart is used to monitor the number of defects per unit for process output.

True

T/F Approximately 99.7 percent of sample means will fall within plus or minus two standard deviations of the process mean if the process is under control.

.16

The chair of the operations management department at Quality University wants to construct a p-chart for determining whether the four faculty teaching the basic P/OM course are under control with regard to the number of students who fail the course. Accordingly, he sampled 100 final grades from last year for each instructor, with the following results: Instructor: Number of Fails: A 13 B 0 C 11 D 16 What is the sample proportion of failures (p) for Prof. D? 0 .04 .11 .13 .16

C.) 4

The following data occurs chronologically from left to right: 15.2 19.7 16.0 11.1 14.8 14.5 The number of runs up and down is: A.) 2. B.) 3. C.) 4. D.) 5. E.) none of these.

C.) Eliminate each of the defects as they are identified

Which of the following is not a step in the quality control process? A.) Define what is to be controlled. B.) Compare measurements to a standard. C.) Eliminate each of the defects as they are identified. D.) Take corrective action if necessary. E.) Evaluate corrective action.

Assignable

_______ variation is a variation whose cause can be identified. Assignable Controllable Random Statistical Theoretical