Question 1

If the lower limit for a p-chart computes to a number less than zero,this indicates:
A)that the lower limit should be set at zero.
B)that the process is out of control.
C)that an attribute measure is incorrectly used.
D)that a calculation error has been made.

Accepted Answer

A lower limit cannot be less than zero because it represents a percentage or a proportion, which cannot be negative. Therefore, the lower limit should be set at zero. This situation does not necessarily indicate any process issue or calculation error.

Question 2

Discuss the differences between attributes and variables data.

Accepted Answer

The answer of Discuss the differences between attributes and variables...

Question 3

A specification is 50.0 cm ± 10.0 cm.Sketch and label the pre-control zones for this specification.Include the following values on your sketch: nominal,upper and lower specification limits,and end points of the green zone.

Accepted Answer

The answer of A specification is 50.0 cm ± 10.0...

Question 4

A canning company defines a "nonconformance" as an orange juice can whose diameter is beyond the upper specification limit.A manager at the canning company wants to monitor the number of such orange juice cans produced per day.Each day,an employee will randomly select 120 cans over a period of four weeks.The employee then determines and plots the number of nonconformance cans in each sample.The appropriate control chart is a(n):
A)u-chart.
B)R-chart.
C)p-chart.
D)np-chart.

Accepted Answer

The np-chart is used for monitoring the number of defective items in a fixed sample size, which aligns with the scenario of counting nonconforming cans out of a fixed sample of 120 cans per day.

Question 5

A _____ monitors the fraction of nonconforming units.
A)c-chart
B)u-chart
C)np-chart
D)p-chart

Accepted Answer

A p-chart is used to monitor the proportion or fraction of defective items in a process, making it the correct choice for monitoring the fraction of nonconforming units.

Question 6

x-charts are used for:
A)averages of variables data.
B)individual attributes data.
C)individual variables data.
D)averages of attributes data.

Accepted Answer

x-charts are used for monitoring and controlling individual variables data over time. They are specifically used to detect any shifts or trends in the individual data points that occur over time.

Question 7

25 samples of size 100 were collected and a total of 96 nonconforming items were found.The upper control limit for a p-chart would be:
A)0.083.
B)0.096.
C)0.137.
D)0.254.

Accepted Answer

The answer of 25 samples of size 100 were collected...

Question 8

The sample size for an x-chart:
A)should be between 25 and 30.
B)is larger than that for an $ \bar{x} $-chart.
C)is equal to one.
D)should be greater than one.

Accepted Answer

The answer of The sample size for an x-chart:
A)should be...

Question 9

Each day,a manufacturing company producing circuit boards will randomly sample 60 circuit boards for a period of 25 days and then determine and plot the number of defects contained in each of these boards.The appropriate control chart is a(n):
A)u-chart.
B)p-chart.
C)np-chart.
D)c-chart.

Accepted Answer

The correct choice is a c-chart because it is used for monitoring the number of defects per unit when the number of opportunities for each defect is constant. In this scenario, the company is tracking the number of defects in a constant sample size (60 circuit boards), making the c-chart the appropriate tool.

Question 10

All else being constant,if the sample size in a p-chart increases from 100 to 120,the upper and lower control limits will:
A)move farther apart.
B)move closer together.
C)not be affected.
D)both shift upward.

Accepted Answer

When the sample size in a p-chart increases, the standard error decreases because it is inversely related to the square root of the sample size. This causes the upper and lower control limits, which are calculated based on the standard error, to move closer together.

Question 11

A delivery company defines a "defect" as a package delivered later than the promised delivery time.Management wants to monitor the proportion of such defect packages per week and plans to sample 120 packages every week.The appropriate control chart is a(n):
A) $ \bar{x} $-chart.
B)R-chart.
C)p-chart.
D)np-chart.

Accepted Answer

Since the attribute being monitored here is the proportion of defective packages (late delivery), the appropriate control chart is a p-chart. This is because a p-chart is used to monitor the proportion of nonconforming items or defects in a sample over time. The other options are not appropriate for this scenario- a $ \bar{x} $-chart is used to monitor continuous data, an R-chart is used to monitor the variation in a process, and an np-chart is used when a fixed number of items are sampled each time.

Question 12

Which of the following charts is used to monitor the average number of nonconformances per unit when sample sizes vary?
A) $ \bar{x} $-chart
B)u-chart
C)p-chart
D)c-chart

Accepted Answer

The u-chart is used to monitor the average number of nonconformances per unit when sample sizes vary. The $ \bar{x} $-chart is used to monitor the average of a continuous process, the p-chart is used to monitor the proportion (or percent) of nonconforming items in a sample, and the c-chart is used to monitor the count of nonconformities per unit when the sample size is constant.

Question 13

Which of the following is a major advantage of np-charts?
A)They can be used for variable sample sizes.
B)They are more accurate than p-charts.
C)They are easier to understand for production personnel.
D)The control limits are based on binomial distribution.

Accepted Answer

np-charts are easier to understand for production personnel because they directly show the number of defective items, making them more intuitive than p-charts which show proportions.

Question 14

Which of the following is CORRECT regarding an x-chart?
A)Individual data require averaging before being plotted on it.
B)It is less sensitive to many conditions that can be detected by $ \bar{x} $-chart and R-chart.
C)Specification limits cannot be drawn on the chart for direct comparison with the control limits.
D)The assumption of normality of observations is less critical than for $ \bar{x} $-chart and R-charts.

Accepted Answer

The answer of Which of the following is CORRECT regarding...

Question 15

To form rational subgroups for an $ \bar{x} $-chart,the goal is to choose the samples as _____ as possible.
A)heterogeneous
B)homogeneous
C)large
D)systematic

Accepted Answer

The goal of forming rational subgroups for an $ \bar{x} $-chart is to select samples that are as homogeneous as possible. Homogeneous samples will have similar variation and will allow for better interpretation of the chart. Heterogeneous samples may result in excessive variation, making it difficult to differentiate between common cause and special cause variation. Therefore, the best choice is option B - homogeneous.

Question 16

Define pre-control and explain under what conditions pre-control can be used.

Accepted Answer

The answer of Define pre-control and explain under what conditions...

Question 17

Because of high test costs,a sample of single wastewater sludge is tested daily for dissolved oxygen content.The appropriate control chart is:
A) $ \bar{x} $-chart and R-chart.
B)u-chart.
C)x-chart and moving range chart.
D)x-chart and R-chart.

Accepted Answer

The x-chart and moving range chart are appropriate for monitoring the dissolved oxygen content in a single wastewater sludge sample tested daily. This is because the x-chart is used for individual measurements rather than averages, and the moving range chart helps monitor the variability between individual measurements, which is suitable for situations where samples are taken individually over time.

Question 18

c-charts are based on the _____ probability distribution.
A)normal
B)binomial
C)Poisson
D)exponential

Accepted Answer

c-charts are used for counting the number of defects or occurrences of an event in a given unit of measurement. This type of data follows a Poisson distribution, which models the probability of rare events occurring in a fixed interval of time or space. Therefore, the correct choice is (C) Poisson. The other distributions listed (normal, binomial, and exponential) are not applicable for c-charts.

Question 19

The control chart most appropriate for plotting the daily percentage of students that wait longer than 5 minutes in line at the undergraduate admissions office is a(n):
A)p-chart.
B)np-chart.
C)x-chart.

Accepted Answer

The p-chart is used when the data being collected involves a proportion or percentage. In this case, we are interested in the percentage of students who wait longer than 5 minutes in line. The p-chart is designed to monitor the proportion of nonconforming items in a sample, making it the most appropriate control chart for this situation.

Question 20

For statistical process control,a good sampling method should always:
A)use samples of random measurements over a long period of time.
B)minimize sampling cost.
C)maximize sample size.
D)use rational subgroups.

Accepted Answer

Using rational subgroups is the best choice as it ensures that the samples are similar and representative of the process being monitored, allowing for accurate control limits to be set based on common cause variation. Random measurements over time (A) may not be representative of the process and could include special cause variation, and may be more costly than using rational subgroups. Minimizing sampling cost (B) and maximizing sample size (C) are important considerations but are secondary to using rational subgroups for accurate control limits.

Quiz 8: Measuring and Controlling Quality

If the lower limit for a p-chart computes to a number less than zero,this indicates:

Discuss the differences between attributes and variables data.

A specification is 50.0 cm ± 10.0 cm.Sketch and label the pre-control zones for this specification.Include the following values on your sketch: nominal,upper and lower specification limits,and end points of the green zone.

A _____ monitors the fraction of nonconforming units.

x-charts are used for:

25 samples of size 100 were collected and a total of 96 nonconforming items were found.The upper control limit for a p-chart would be:

The sample size for an x-chart:

Each day,a manufacturing company producing circuit boards will randomly sample 60 circuit boards for a period of 25 days and then determine and plot the number of defects contained in each of these boards.The appropriate control chart is a(n) :

All else being constant,if the sample size in a p-chart increases from 100 to 120,the upper and lower control limits will:

A delivery company defines a "defect" as a package delivered later than the promised delivery time.Management wants to monitor the proportion of such defect packages per week and plans to sample 120 packages every week.The appropriate control chart is a(n) :

Which of the following charts is used to monitor the average number of nonconformances per unit when sample sizes vary?

Which of the following is a major advantage of np-charts?

Which of the following is CORRECT regarding an x-chart?

To form rational subgroups for an $\bar{x}$ -chart,the goal is to choose the samples as _____ as possible.

Define pre-control and explain under what conditions pre-control can be used.

Because of high test costs,a sample of single wastewater sludge is tested daily for dissolved oxygen content.The appropriate control chart is:

c-charts are based on the _____ probability distribution.

The control chart most appropriate for plotting the daily percentage of students that wait longer than 5 minutes in line at the undergraduate admissions office is a(n) :

For statistical process control,a good sampling method should always:

Quiz 8: Measuring and Controlling Quality

If the lower limit for a p-chart computes to a number less than zero,this indicates:

Discuss the differences between attributes and variables data.

A specification is 50.0 cm ± 10.0 cm.Sketch and label the pre-control zones for this specification.Include the following values on your sketch: nominal,upper and lower specification limits,and end points of the green zone.

A _____ monitors the fraction of nonconforming units.

x-charts are used for:

25 samples of size 100 were collected and a total of 96 nonconforming items were found.The upper control limit for a p-chart would be:

The sample size for an x-chart:

Each day,a manufacturing company producing circuit boards will randomly sample 60 circuit boards for a period of 25 days and then determine and plot the number of defects contained in each of these boards.The appropriate control chart is a(n) :

All else being constant,if the sample size in a p-chart increases from 100 to 120,the upper and lower control limits will:

A delivery company defines a "defect" as a package delivered later than the promised delivery time.Management wants to monitor the proportion of such defect packages per week and plans to sample 120 packages every week.The appropriate control chart is a(n) :

Which of the following charts is used to monitor the average number of nonconformances per unit when sample sizes vary?

Which of the following is a major advantage of np-charts?

Which of the following is CORRECT regarding an x-chart?

To form rational subgroups for an xˉ \bar{x} xˉ -chart,the goal is to choose the samples as _____ as possible.

Define pre-control and explain under what conditions pre-control can be used.

Because of high test costs,a sample of single wastewater sludge is tested daily for dissolved oxygen content.The appropriate control chart is:

c-charts are based on the _____ probability distribution.

The control chart most appropriate for plotting the daily percentage of students that wait longer than 5 minutes in line at the undergraduate admissions office is a(n) :

For statistical process control,a good sampling method should always:

To form rational subgroups for an $\bar{x}$ -chart,the goal is to choose the samples as _____ as possible.