Deck 17: Statistical Applications in Quality Management

Question 1

TABLE 17-2
A political pollster randomly selects a sample of 100 voters each day for 8 successive days and asks how many will vote for the incumbent. The pollster wishes to construct a p chart to see if the percentage favoring the incumbent candidate is too erratic.
Referring to Table 17-2, which expression best characterizes the p chart?

A) In-control
B) Increasing trend
C) Decreasing trend
D) Individual outliers

Answer 1

A

Question 2

TABLE 17-1
A local newspaper has 10 delivery boys who each deliver the morning paper to 50 customers every day. The owner decides to record the number of papers delivered on time for a 10-day period for one of the delivery boys and construct a p chart to see whether the percentage is too erratic.
Referring to Table 17-1, which expression best characterizes the p chart?

A) Cycles
B) Increasing trend
C) In-control
D) Individual outliers

Answer 2

C

Question 3

One of the morals of the red bead experiment is

A) variation is part of the process.
B) only management can change the system.
C) it is the system that primarily determines performance.
D) All of the above.

Answer 3

D

Question 4

The principal focus of the control chart is the attempt to separate special or assignable causes of variation from common causes of variation. Which causes of variation can be reduced only by changing the system?

A) Special or assignable causes
B) Common causes
C) Total causes
D) None of the above

Question 5

TABLE 17-2
A political pollster randomly selects a sample of 100 voters each day for 8 successive days and asks how many will vote for the incumbent. The pollster wishes to construct a p chart to see if the percentage favoring the incumbent candidate is too erratic.
Referring to Table 17-2, what is the numerical value of the center line for the p chart?

A) 0.53
B) 0.56
C) 0.63
D) 0.66

Question 6

Which of the following situations suggests a process that appears to be operating in a state of statistical control?

A) A control chart with a series of consecutive points that are above the center line and a series of consecutive points that are below the center line
B) A control chart in which no points fall outside either the upper control limit or the lower control limit and no patterns are present
C) A control chart in which several points fall outside the upper control limit
D) All of the above.

Question 7

The control chart

A) focuses on the time dimension of a system.
B) captures the natural variability in the system.
C) can be used for categorical, discrete, or continuous variables.
D) All of the above.

Question 8

TABLE 17-2
A political pollster randomly selects a sample of 100 voters each day for 8 successive days and asks how many will vote for the incumbent. The pollster wishes to construct a p chart to see if the percentage favoring the incumbent candidate is too erratic.
Referring to Table 17-2, what is the numerical value of the upper control limit for the p chart?

A) 0.92
B) 0.89
C) 0.71
D) 0.62

Question 9

TABLE 17-3
A quality control analyst for a light bulb manufacturer is concerned that the time it takes to produce a batch of light bulbs is too erratic. Accordingly, the analyst randomly surveys 10 production periods each day for 14 days and records the sample mean and range for each day.

Referring to Table 17-3, suppose the analyst constructs an R chart to see if the variability in production times is in-control. What is the upper control limit for this R chart?

A) 10.66
B) 9.37
C) 7.98
D) 6.34

Question 10

Once the control limits are set for a control chart, one attempts to

A) discern patterns that might exist in values over time.
B) determine whether any points fall outside the control limits.
C) Both of the above.
D) None of the above.

Question 11

Variation signaled by individual fluctuations or patterns in the data is called

A) special or assignable causes.
B) common or chance causes.
C) explained variation.
D) the standard deviation.

Question 12

Variation due to the inherent variability in a system of operation is called

A) special or assignable causes.
B) common or chance causes.
C) explained variation.
D) the standard deviation.

Question 13

TABLE 17-1
A local newspaper has 10 delivery boys who each deliver the morning paper to 50 customers every day. The owner decides to record the number of papers delivered on time for a 10-day period for one of the delivery boys and construct a p chart to see whether the percentage is too erratic.
Referring to Table 17-1, what is the numerical value of the lower control limit for the p chart?

A) 0.920
B) 0.911
C) 0.815
D) 0.798

Question 14

TABLE 17-1
A local newspaper has 10 delivery boys who each deliver the morning paper to 50 customers every day. The owner decides to record the number of papers delivered on time for a 10-day period for one of the delivery boys and construct a p chart to see whether the percentage is too erratic.
Referring to Table 17-1, what is the numerical value of the upper control limit for the p chart?

A) 0.926
B) 0.961
C) 0.979
D) 1.037

Question 15

TABLE 17-3
A quality control analyst for a light bulb manufacturer is concerned that the time it takes to produce a batch of light bulbs is too erratic. Accordingly, the analyst randomly surveys 10 production periods each day for 14 days and records the sample mean and range for each day.

Referring to Table 17-3, suppose the analyst constructs an R chart to see if the variability in production times is in-control. What is the center line of this R chart?

A) 4.8
B) 6.0
C) 6.9
D) 7.1

Question 16

A process is said to be out of control if

A) a point falls above the upper or below the lower control lines.
B) eight or more consecutive points fall above the center line or eight or more consecutive points fall below the center line.
C) Either of the above.
D) None of the above.

Question 17

TABLE 17-2
A political pollster randomly selects a sample of 100 voters each day for 8 successive days and asks how many will vote for the incumbent. The pollster wishes to construct a p chart to see if the percentage favoring the incumbent candidate is too erratic.
Referring to Table 17-2, what is the numerical value of the lower control limit for the p chart?

A) 0.37
B) 0.41
C) 0.50
D) 0.71

Question 18

Which of the following situations suggests a process that appears to be operating out of statistical control?

A) A control chart with a series of consecutive points that are above the center line and a series of consecutive points that are below the center line
B) A control chart in which points fall outside the lower control limit
C) A control chart in which several points fall outside the upper control limit
D) All of the above.

Question 19

TABLE 17-3
A quality control analyst for a light bulb manufacturer is concerned that the time it takes to produce a batch of light bulbs is too erratic. Accordingly, the analyst randomly surveys 10 production periods each day for 14 days and records the sample mean and range for each day.

Referring to Table 17-3, suppose the analyst constructs an R chart to see if the variability in production times is in-control. What is the lower control limit for this R chart?

A) 4.84
B) 3.37
C) 2.98
D) 1.34

Question 20

TABLE 17-1
A local newspaper has 10 delivery boys who each deliver the morning paper to 50 customers every day. The owner decides to record the number of papers delivered on time for a 10-day period for one of the delivery boys and construct a p chart to see whether the percentage is too erratic.
Referring to Table 17-1, what is the numerical value of the center line for the p chart?

A) 0.926
B) 0.911
C) 0.885
D) 0.500

Question 21

The control limits are based on the standard deviation of the process.

Question 22

Referring to Table 17-4, suppose the supervisor constructs an chart to see if the process is in-control. What is the center line of the chart?

A) 20.00
B) 20.26
C) 21.00
D) 24.26

Question 23

Referring to Table 17-3, suppose the analyst constructs an chart to see if the production process is in-control. Which expression best describes this chart?

A) In-control
B) Increasing trend
C) Decreasing trend
D) Individual outliers

Question 24

Referring to Table 17-4, what percentage of the time it takes workers to complete an important production task will fall inside the specification limits?

Question 25

Referring to Table 17-4, what is the value of the CPL index?

Question 26

TABLE 17-4
A factory supervisor is concerned that the time it takes workers to complete an important production task (measured in seconds) is too erratic and adversely affects expected profits. The supervisor proceeds by randomly sampling 5 individuals per hour for a period of 10 hours. The sample mean and range for each hour are listed below.

She also decides that lower and upper specification limit for the critical-to-quality variable should be 10 and 30 seconds, respectively.
Referring to Table 17-4, suppose the supervisor constructs an R chart to see if the variability in collection times is in-control. What is the center line of this R chart?

A) 20.00
B) 20.56
C) 20.40
D) 24.00

Question 27

Referring to Table 17-4, suppose the supervisor constructs an chart to see if the process is in-control. What are the lower and upper control limits of this chart?

A) 10.00, 30.00
B) 8.49, 32.03
C) 5.39, 35.13
D) 4.96, 35.56

Question 28

Referring to Table 17-4, what is the value of the Cpk index?

Question 29

Referring to Table 17-4, what is the value of the Cp index?

Question 30

Referring to Table 17-4, suppose the supervisor constructs an chart to see if the process is in-control. Which expression best describes this chart?

A) Decreasing trend
B) In-control
C) Increasing trend
D) Individual outliers

Question 31

TABLE 17-4
A factory supervisor is concerned that the time it takes workers to complete an important production task (measured in seconds) is too erratic and adversely affects expected profits. The supervisor proceeds by randomly sampling 5 individuals per hour for a period of 10 hours. The sample mean and range for each hour are listed below.

She also decides that lower and upper specification limit for the critical-to-quality variable should be 10 and 30 seconds, respectively.
Referring to Table 17-4, suppose the supervisor constructs an R chart to see if the variability in collection times is in-control. What are the lower and upper control limits for this R chart?

A) -2.33, 43.13
B) -2.28, 42.28
C) 0, 42.28
D) 0, 43.13

Question 32

TABLE 17-4
A factory supervisor is concerned that the time it takes workers to complete an important production task (measured in seconds) is too erratic and adversely affects expected profits. The supervisor proceeds by randomly sampling 5 individuals per hour for a period of 10 hours. The sample mean and range for each hour are listed below.

She also decides that lower and upper specification limit for the critical-to-quality variable should be 10 and 30 seconds, respectively.
Referring to Table 17-4, suppose the supervisor constructs an R chart to see if the variability in collection times is in-control. This R chart is characterized by which of the following?

A) Decreasing trend
B) Increasing trend
C) In-control
D) Individual outliers

Question 33

Referring to Table 17-4, what is the value of d₂ factor?

Question 34

Referring to Table 17-3, suppose the analyst constructs an chart to see if the production process is in-control. What is the lower control limit (LCL) for this chart?

A) 47.60
B) 56.15
C) 57.15
D) 58.05

Question 35

Referring to Table 17-4, what is the value of the CPU index?

Question 36

TABLE 17-3
A quality control analyst for a light bulb manufacturer is concerned that the time it takes to produce a batch of light bulbs is too erratic. Accordingly, the analyst randomly surveys 10 production periods each day for 14 days and records the sample mean and range for each day.

Referring to Table 17-3, suppose the sample mean and range data were based on 11 observations per day instead of 10. How would this change affect the lower and upper control limits of the R chart?

A) LCL would increase; UCL would decrease.
B) LCL would remain the same; UCL would decrease.
C) Both LCL and UCL would remain the same.
D) LCL would decrease; UCL would increase.

Question 37

TABLE 17-4
A factory supervisor is concerned that the time it takes workers to complete an important production task (measured in seconds) is too erratic and adversely affects expected profits. The supervisor proceeds by randomly sampling 5 individuals per hour for a period of 10 hours. The sample mean and range for each hour are listed below.

She also decides that lower and upper specification limit for the critical-to-quality variable should be 10 and 30 seconds, respectively.
Referring to Table 17-4, suppose the sample mean and range data were based on 6 observations per hour instead of 5. How would this change affect the lower and upper control limits of an R chart?

A) LCL would increase; UCL would decrease.
B) LCL would remain the same; UCL would decrease.
C) Both LCL and UCL would remain the same.
D) LCL would decrease; UCL would increase.

Question 38

TABLE 17-3
A quality control analyst for a light bulb manufacturer is concerned that the time it takes to produce a batch of light bulbs is too erratic. Accordingly, the analyst randomly surveys 10 production periods each day for 14 days and records the sample mean and range for each day.

Referring to Table 17-3, suppose the analyst constructs an R chart to see if the variability in production times is in-control. The R chart is characterized by which of the following?

A) Increasing trend
B) Decreasing trend
C) In-control
D) Points outside the control limits

Question 39

Referring to Table 17-3, suppose the analyst constructs an chart to see if the production process is in-control. What is the upper control limit (UCL) for this chart?

A) 62.15
B) 60.95
C) 59.85
D) 58.75

Question 40

Referring to Table 17-3, suppose the analyst constructs an chart to see if the production process is in-control. What is the center line for this chart?

A) 64.3
B) 59.5
C) 58.0
D) 57.1

Question 41

Changes in the system to reduce common cause variation are the responsibility of management.

Question 42

The purpose of a control chart is to eliminate common cause variation.

Question 43

It is not possible for the chart to be out of control when the R chart is in control.

Question 44

TABLE 17-5
A manufacturer of computer disks took samples of 240 disks on 15 consecutive days. The number of disks with bad sectors was determined for each of these samples. The results are in the table that follows.
Referring to Table 17-5, the process seems to be in control.

Question 45

TABLE 17-5
A manufacturer of computer disks took samples of 240 disks on 15 consecutive days. The number of disks with bad sectors was determined for each of these samples. The results are in the table that follows.
Referring to Table 17-5, a p control chart is to be made for these data. The upper control limit is ________, and the lower control limit is ________.

Question 46

TABLE 17-5
A manufacturer of computer disks took samples of 240 disks on 15 consecutive days. The number of disks with bad sectors was determined for each of these samples. The results are in the table that follows.
Referring to Table 17-5, a p control chart is to be made for these data. The center line of the control chart is ________.

Question 47

The cause of variation that can be reduced only by changing the system is ________ cause variation.

Question 48

________ causes of variation are correctable without modifying the system.

Question 49

TABLE 17-5
A manufacturer of computer disks took samples of 240 disks on 15 consecutive days. The number of disks with bad sectors was determined for each of these samples. The results are in the table that follows.
Referring to Table 17-5, the best estimate of the mean proportion of disks with bad sectors is ________.

Question 50

TABLE 17-6
The maker of a packaged candy wants to evaluate the quality of her production process. On each of 16 consecutive days, she samples 600 bags of candy and determines the number in each day's sample that she considers to be of poor quality. The data that she developed follow.
Referring to Table 17-6, a p control chart is to be constructed for these data. The center line for the chart should be located at ________.

Question 51

TABLE 17-5
A manufacturer of computer disks took samples of 240 disks on 15 consecutive days. The number of disks with bad sectors was determined for each of these samples. The results are in the table that follows.
Referring to Table 17-5, construct a p control chart for these data.

Question 52

TABLE 17-6
The maker of a packaged candy wants to evaluate the quality of her production process. On each of 16 consecutive days, she samples 600 bags of candy and determines the number in each day's sample that she considers to be of poor quality. The data that she developed follow.
Referring to Table 17-6, the estimate of the proportion of poor quality bags of candy is ________.

Question 53

In the United States, the control limits on a control chart are placed so that they are 3 standard deviations above and below a central line.

Question 54

The p chart is a control chart used for monitoring the proportion of items that meet given specifications.

Question 55

TABLE 17-5
A manufacturer of computer disks took samples of 240 disks on 15 consecutive days. The number of disks with bad sectors was determined for each of these samples. The results are in the table that follows.
Referring to Table 17-5, a p control chart is to be made for these data. The estimate of the standard error of the proportion of disks with bad sectors is ________.

Question 56

One of the morals of the red bead experiment is that variation is part of any process.

Question 57

The R chart is a control chart used to monitor a process mean.

Question 58

Special or assignable causes of variation are signaled by individual fluctuations or patterns in the data.

Question 59

Common causes of variation represent variation due to the inherent variability in the system.

Question 60

Common causes of variation are correctable without modifying the system.

Question 61

TABLE 17-6
The maker of a packaged candy wants to evaluate the quality of her production process. On each of 16 consecutive days, she samples 600 bags of candy and determines the number in each day's sample that she considers to be of poor quality. The data that she developed follow.
Referring to Table 17-6, a p control chart is to be constructed for these data. The estimate of the standard error of the sample proportion is ________.

Question 62

Referring to Table 17-7, what is the value of d₂ factor?

Question 63

TABLE 17-8
Recently, a university switched to a new type of computer-based registration. The registrar is concerned with the amount of time students are spending on the computer registering under the new system. She decides to randomly select 8 students on each of the 12 days of the registration and determine the time each spends on the computer registering. The range, mean, and standard deviation of the times required to register are in the table that follows.
Referring to Table 17-8, an R chart is to be constructed for the time required to register. The center line of this R chart is located at ________.

Question 64

Referring to Table 17-7, construct an chart for the number of blemishes.

Question 65

TABLE 17-7
A supplier of silicone sheets for producers of computer chips wants to evaluate her manufacturing process. She takes samples of size 5 from each day's output and counts the number of blemishes on each silicone sheet. The results from 20 days of such evaluations are presented below.
Referring to Table 17-7, an R chart is to be constructed for the number of blemishes. The upper control limit for this data set is ________.

Question 66

Referring to Table 17-7, an chart is to be used for the number of blemishes. The center line of this chart is located at ________.

Question 67

TABLE 17-7
A supplier of silicone sheets for producers of computer chips wants to evaluate her manufacturing process. She takes samples of size 5 from each day's output and counts the number of blemishes on each silicone sheet. The results from 20 days of such evaluations are presented below.
Referring to Table 17-7, an R chart is to be constructed for the number of blemishes. One way to create the upper control limit involves multiplying the mean of the sample ranges by D₄. For this data set, the value of D₄ is ________.

Question 68

TABLE 17-7
A supplier of silicone sheets for producers of computer chips wants to evaluate her manufacturing process. She takes samples of size 5 from each day's output and counts the number of blemishes on each silicone sheet. The results from 20 days of such evaluations are presented below.
Referring to Table 17-7, an R chart is to be constructed for the number of blemishes. The center line of this R chart is located at ________.

Question 69

TABLE 17-7
A supplier of silicone sheets for producers of computer chips wants to evaluate her manufacturing process. She takes samples of size 5 from each day's output and counts the number of blemishes on each silicone sheet. The results from 20 days of such evaluations are presented below.
Referring to Table 17-7, based on the R chart, it appears that the process is out of control.

Question 70

TABLE 17-6
The maker of a packaged candy wants to evaluate the quality of her production process. On each of 16 consecutive days, she samples 600 bags of candy and determines the number in each day's sample that she considers to be of poor quality. The data that she developed follow.
Referring to Table 17-6, a p control chart is to be constructed for these data. The lower control limit is ________, while the upper control limit is ________.

Question 71

TABLE 17-6
The maker of a packaged candy wants to evaluate the quality of her production process. On each of 16 consecutive days, she samples 600 bags of candy and determines the number in each day's sample that she considers to be of poor quality. The data that she developed follow.
Referring to Table 17-6, construct a p control chart for these data.

Question 72

Referring to Table 17-7, an chart is to be used for the number of blemishes. The lower control limit for this data set is ________, while the upper control limit is ________.

Question 73

TABLE 17-7
A supplier of silicone sheets for producers of computer chips wants to evaluate her manufacturing process. She takes samples of size 5 from each day's output and counts the number of blemishes on each silicone sheet. The results from 20 days of such evaluations are presented below.
Referring to Table 17-7, an R chart is to be constructed for the number of blemishes. One way to create the lower control limit involves multiplying the mean of the sample ranges by D₃. For this data set, the value of D₃ is ________.

Question 74

Referring to Table 17-7, what is the value of the CPU index?

Question 75

Referring to Table 17-7, based on the chart for the number of blemishes, it appears that the process is out of control.

Question 76

TABLE 17-7
A supplier of silicone sheets for producers of computer chips wants to evaluate her manufacturing process. She takes samples of size 5 from each day's output and counts the number of blemishes on each silicone sheet. The results from 20 days of such evaluations are presented below.
Referring to Table 17-7, an R chart is to be constructed for the number of blemishes. The lower control limit for this data set is ________.

Question 77

TABLE 17-7
A supplier of silicone sheets for producers of computer chips wants to evaluate her manufacturing process. She takes samples of size 5 from each day's output and counts the number of blemishes on each silicone sheet. The results from 20 days of such evaluations are presented below.
Referring to Table 17-7, construct an R chart for the number of blemishes.

Question 78

Referring to Table 17-7, what percentage of the chips will fall below the upper specification limit?

Question 79

TABLE 17-6
The maker of a packaged candy wants to evaluate the quality of her production process. On each of 16 consecutive days, she samples 600 bags of candy and determines the number in each day's sample that she considers to be of poor quality. The data that she developed follow.
Referring to Table 17-6, the process seems to be in control.

Question 80

Referring to Table 17-7, an chart is to be used for the number of blemishes. One way to obtain the control limits is to take the grand mean and add and subtract the product of A₂ times the mean of the sample ranges. For this data set, the value of A₂ is ________.