Deck 12: Statistically Based Quality Improvement for Attributes

Question 1

Use the following table to answer the question(s) below.

A manufacturer of FAX machines checks samples of 50 units for functionality at the conclusion of the assembly process. The results of 10 samples are shown below:
What sample is out of control?

A) 1
B) 2
C) 3
D) 4
E) none of the samples are out of control

Answer 1

B

Question 2

________ attributes relate to time.

A) Structural
B) Sensory
C) Performance
D) Temporal
E) Tactile

Answer 2

D

Question 3

Use the following table to answer the question(s) below.

A producer of contact lenses regularly takes samples of 100 lenses and inspects them for scratches. If a lens has a single scratch, it cannot be sold. The results of 10 samples are shown below: What sample is out of control?

A) 2
B) 4
C) 6
D) 8
E) none of the samples are out of control

Answer 3

E

Question 4

________ attributes relate to the physical characteristics of a particular product or service.

A) Structural
B) Sensory
C) Performance
D) Temporal
E) Ethical

Question 5

Use the following table to answer the question(s) below.

A manufacturer of FAX machines checks samples of 50 units for functionality at the conclusion of the assembly process. The results of 10 samples are shown below: What is the average proportion defective?

A) 0.07
B) 0.14
C) 0.21
D) 0.28
E) 0.35

Question 6

________ attributes relate to senses of touch, smell, taste, and sound.

A) Structural
B) Sensory
C) Performance
D) Consensual
E) Ethical

Question 7

Use the following table to answer the question(s) below.

A producer of contact lenses regularly takes samples of 100 lenses and inspects them for scratches. If a lens has a single scratch, it cannot be sold. The results of 10 samples are shown below: What is the average proportion defective?

A) 0.012
B) 0.014
C) 0.020
D) 0.028
E) 0.035

Question 8

Defectives are monitored using ________.

A) c charts
B) g charts
C) u charts
D) p charts
E) d charts

Question 9

Use the following table to answer the question(s) below.

The producers of the Yugo automobile periodically inspect samples of 80 hoods for dents and scratches. A single flaw in a hood renders it unsuitable for installation in one of their fine automobiles. The results of the last 10 samples are shown below. Calculate the standard error, snp, for the np chart.

A) 7.75
B) 0.10
C) 0.31
D) 2.78
E) 2.95

Question 10

The first step in developing an attribute process chart is to ________.

A) determine whether the critical product characteristic is a variable or an attribute
B) establish control limits
C) identify critical product characteristics
D) identify critical operations where process inspection might be needed
E) select the appropriate process chart from the many types of charts

Question 11

An irregularity or problem with a larger unit is a(n) ________.

A) defect
B) defective
C) flaw
D) mistake
E) error

Question 12

Use the following table to answer the question(s) below.

A producer of contact lenses regularly takes samples of 100 lenses and inspects them for scratches. If a lens has a single scratch, it cannot be sold. The results of 10 samples are shown below: What are the lower and upper 3-sigma control limits?

A) (-0.021, 0.012)
B) (-0.021, 0.000)
C) (0.012, 0.035)
D) (0.000, 0.035)
E) (0.000, 0.049)

Question 13

________ attributes relate to whether or not a particular product or service performs as it is supposed to.

A) Structural
B) Sensory
C) Performance
D) Temporal
E) Ethical

Question 14

Use the following table to answer the question(s) below.

A manufacturer of FAX machines checks samples of 50 units for functionality at the conclusion of the assembly process. The results of 10 samples are shown below: What are the lower and upper 3-sigma control limits?

A) (-0.01, 0.09)
B) (-0.01, 0.00)
C) (-0.01, 0.09)
D) (0.00, 0.09)
E) (0.00, 0.29)

Question 15

A painter paints a wall and when too much paint is applied, drips result. In the language of attribute charts, the drips are ________.

A) defectives
B) defects
C) variables
D) critical
E) temporal

Question 16

________ attributes answer whether a service provider is empathetic or if their accounting systems report properly.

A) Structural
B) Sensory
C) Performance
D) Temporal
E) Ethical

Question 17

Which of the following is not used for monitoring defects or defectives?

A) p charts
B) np charts
C) u charts
D) c charts
E) r charts

Question 18

A unit that, as a whole, is not acceptable or does not meet performance requirements is a(n) ________.

A) defect
B) defective
C) flaw
D) mistake
E) error

Question 19

Which of the following is an example of a statistic based on an attribute?

A) s (standard deviation)
B) R (range)
C) p (proportion defective)
D) MR (moving range)
E) X bar (process population average)

Question 20

Attributes that are more internal and engineering-oriented are called ________ attributes.

A) structural
B) sensory
C) performance
D) customer-based
E) production-related

Question 21

A system is to be composed of 5 identical components in series. What is the lowest reliability component that can be used in order to have an overall system reliability of 0.90?

A) 0.98
B) 0.97
C) 0.96
D) 0.95
E) 0.94

Question 22

Use the following table to answer the question(s) below.

A parks and recreation worker counts the number of paint drips on each standard size park bench. The results from the last 10 benches are shown below. If the Parks Department decides to make a c chart, what should the lower and upper 3-sigma control limits be?

A) (-9.2, 9.2)
B) (0.0, 20)
C) (0.1, 18.3)
D) (3.1, 13.1)
E) (3.1, 18.3)

Question 23

A system is composed of three components. Two of the items are in parallel and have reliabilities of 0.95 and 0.90. The third item has a reliability of 0.98 and this item is in series with the first combination. What is the overall system reliability?

A) 0.995
B) 0.985
C) 0.975
D) 0.965
E) 0.955

Question 24

A quality engineer notes that a process produces data that are binomial and has been obtained using a sample space that is not constant. The primary interest of the process manager is in the percentage of bad parts. An appropriate control chart to use would be a(n) ________.

A) np chart
B) p chart
C) c chart
D) u chart
E) d chart

Question 25

A system is composed of three components in series having reliabilities of 0.99, 0.98, and 0.97. What is the overall system reliability?

A) 0.97
B) 0.96
C) 0.95
D) 0.94
E) 0.93

Question 26

A system is composed of three components in series having reliabilities of 0.85, 0.92, and 0.90. What is the overall system reliability?

A) 0.90
B) 0.85
C) 0.80
D) 0.75
E) 0.70

Question 27

Use the following table to answer the question(s) below.

A parks and recreation worker counts the number of paint drips on each standard size park bench. The results from the last 10 benches are shown below. If the Parks Department decides to make a c chart, what should the center line be?

A) 6.9
B) 8.4
C) 9.2
D) 10.7
E) 11.3

Question 28

The reliability model that shows that products are more likely to fail either very early in their useful life or very late in their useful life is called the ________.

A) half-moon hazard function
B) saucer-shaped hazard function
C) half-circle hazard function
D) cone-shaped hazard function
E) bathtub-shaped hazard function

Question 29

The vertical axis on the bathtub function is ________.

A) failure rate
B) time
C) predicted life
D) design reliability
E) useful life

Question 30

System unreliability is increased with ________.

A) a redundant system
B) a parallel system
C) a backup system
D) high reliability components
E) low reliability components

Question 31

The horizontal axis on the bathtub function is ________.

A) failure rate
B) time
C) useful life
D) design reliability
E) predicted life

Question 32

Use the following table to answer the question(s) below.

The producers of the Yugo automobile periodically inspect samples of 80 hoods for dents and scratches. A single flaw in a hood renders it unsuitable for installation in one of their fine automobiles. The results of the last 10 samples are shown below. What are the lower and upper control limits for the np chart?

A) (-8.35, 2.8)
B) (2.8, 8.35)
C) (0.3, 17.1)
D) (8.7, 17.1)
E) (0.4, 8.7)

Question 33

Use the following table to answer the question(s) below.

The producers of the Yugo automobile periodically inspect samples of 80 hoods for dents and scratches. A single flaw in a hood renders it unsuitable for installation in one of their fine automobiles. The results of the last 10 samples are shown below. What is the center line for the np chart?

A) 2.4
B) 5.8
C) 7.2
D) 8.7
E) 10.1

Question 34

A system is to be composed of 10 identical components in series. What is the lowest reliability component that can be used in order to have an overall system reliability of 0.90?

A) 0.99
B) 0.98
C) 0.97
D) 0.96
E) 0.95

Question 35

A quality engineer notes that a process produces data that are binomial and has been obtained using a sample space that is not constant. The primary interest of the process manager is in the number of discrepancies per part. An appropriate control chart to use would be a(n) ________.

A) np chart
B) p chart
C) c chart
D) u chart
E) d chart

Question 36

Use the following table to answer the question(s) below.

A parks and recreation worker counts the number of paint drips on each standard size park bench. The results from the last 10 benches are shown below. If the Parks Department decides to make a c chart, what bench number is out of control?

A) 1
B) 3
C) 5
D) 7
E) none of these observations are out of control

Question 37

Reliability models assume statistical independence between failure events. This means that ________.

A) components do not fail
B) if one component fails, the entire system fails
C) parallel systems are unnecessary
D) the failure of one component does not influence another to fail
E) series systems are unnecessary

Question 38

Use the following table to answer the question(s) below.

The producers of the Yugo automobile periodically inspect samples of 80 hoods for dents and scratches. A single flaw in a hood renders it unsuitable for installation in one of their fine automobiles. The results of the last 10 samples are shown below. What sample is out of control?

A) 1
B) 3
C) 5
D) 4
E) 10

Question 39

A quality engineer notes that a process produces data that are binomial and has been obtained using a sample space that is constant. The primary interest of the process manager is in the percentage of bad parts. An appropriate control chart to use would be a(n) ________.

A) p chart
B) r chart
C) c chart
D) u chart
E) d chart

Question 40

A system is composed of three components in series having reliabilities of 0.99, 0.95, and 0.90. What is the overall system reliability?

A) 0.95
B) 0.90
C) 0.85
D) 0.80
E) 0.75

Question 41

What is the useful life in hours for a product having a reliability of 0.985 and a failure rate of 0.015 failures per hour?

A) 120
B) 200
C) 280
D) 360
E) 440

Question 42

Fifty defibrillators are tested for 48 hours per machine. Of all the machines tested, 2 experience malfunctions during the test. What is the failure rate for the machines?

A) 0.004
B) 0.042
C) 0.01
D) 0.008
E) 0.0008

Question 43

What is the reliability of a product with a failure rate of 0.001 per operating hour and a useful life of 1500 hours?

A) 0.14
B) 0.22
C) 0.50
D) 0.78
E) 0.86

Question 44

A local university is deciding between three different computer networks. The network servers have a mean time between failure and mean time to repair as shown in the table. MTBF MTTR
Server A 100 hrs 1 hour
Server B 250 hrs 2 hours
Server C 400 hrs 3 hours
Which server(s) will provide the greatest availability?

A) Server A
B) Server B
C) Server C
D) Server A and Server B
E) Server B and Server C

Question 45

Two components of reliability 0.95 are in parallel and this subsystem is connected in series to a component with a reliability of 0.90. The overall system reliability is ________.

A) 0.82
B) 0.84
C) 0.86
D) 0.88
E) 0.90

Question 46

What is the system availability for something that has a mean time between failures of 50 hours and needs an average of 1 hour to repair when it does fail?

A) 0.98
B) 0.92
C) 0.86
D) 0.80
E) 0.74

Question 47

What is the useful life in hours for a product having a reliability of 0.999 and a failure rate of 0.015 failures per hour?

A) 400
B) 420
C) 440
D) 460
E) 480

Question 48

A local university is deciding between three different copy machines. The copy machines have a mean time between failure and mean time to repair as shown in the table. MTBF MTTR
Copier A 48 hrs 1 hour
Copier B 168 hrs 5 hours
Copier C 300 hrs 8 hours
What system(s) will provide the greatest availability?

A) Copier A
B) Copier B
C) Copier C
D) Copier A and Copier B
E) Copier B and Copier C

Question 49

What is the approximate useful life in hours for a product having a reliability of 0.9978 and a failure rate of 0.001 failures per hour?

A) 6120
B) 5600
C) 5000
D) 4400
E) 3800

Question 50

A system has an availability of 90% and a mean time to repair of 48 hours. What is the mean time between failures?

A) 400 hours
B) 432 hours
C) 464 hours
D) 496 hours
E) 528 hours

Question 51

What is the system availability for something that has a mean time between failures of 168 hours and needs an average of 48 hours to repair when it does fail?

A) 0.98
B) 0.93
C) 0.88
D) 0.83
E) 0.78

Question 52

A system is to be composed of 4 identical components in series. What is the lowest reliability component that can be used in order to have an overall system reliability of 0.85?

A) 0.93
B) 0.94
C) 0.95
D) 0.96
E) 0.97

Question 53

A local fraternity is deciding between three different refrigerators. The refrigerators have a mean time between failure and mean time to repair as shown in the table. MTBF MTTR
Refrigerator A 50 hours 2 hours
Refrigerator B 125 hours 3 hours
Refrigerator C 200 hours 4 hours
What refrigerator(s) will provide the greatest availability?

A) Refrigerator A
B) Refrigerator B
C) Refrigerator C
D) Refrigerator A and Refrigerator B
E) Refrigerator A and Refrigerator C

Question 54

Two components of reliability 0.95 are in parallel and this subsystem is connected in series to a component with a reliability of 0.95. The overall system reliability is ________.

A) 0.93
B) 0.94
C) 0.95
D) 0.96
E) 0.97

Question 55

Two components of reliability 0.90 are in parallel and this subsystem is connected in series to a component with a reliability of 0.95. The overall system reliability is ________.

A) 0.93
B) 0.94
C) 0.95
D) 0.96
E) 0.97

Question 56

What is the reliability of a product with a failure rate of 0.015 per operating hour and a useful life of 250 hours?

A) 0.14
B) 0.12
C) 0.88
D) 0.98
E) 0.02

Question 57

What is the reliability of a product with a failure rate of 0.002 per operating hour and a useful life of 1000 hours?

A) 0.14
B) 0.22
C) 0.50
D) 0.78
E) 0.86

Question 58

What is the system availability for something that has a mean time between failures of 100 hours and needs an average of 4 hours to repair when it does fail?

A) 0.98
B) 0.92
C) 0.96
D) 0.90
E) 0.84

Question 59

Structural attributes have to do with physical characteristics of a particular product or service.

Question 60

Fifty crash helmets are tested for one hundred hours per helmet. Of all the helmets tested, only one experiences a malfunction during the test. What is the failure rate for the helmets?

A) 0.0002
B) 0.002
C) 0.004
D) 0.0008
E) 0.016

Question 61

The np chart is a graph of the number of defectives in a subgroup.

Question 62

Two items in parallel having a reliability of 0.90 have an overall system reliability of 0.81.

Question 63

Customer-based attributes are internal and engineering-oriented.

Question 64

Three items of reliability 0.90 in series has an overall system reliability of 0.73.

Question 65

Components in a system are in parallel if the performance of the entire system depends on all its components functioning properly.

Question 66

An attribute is a continuous measurement such as weight, height, or volume.

Question 67

A p chart can be used whether or not there is a constant sample size.

Question 68

A winemaker tastes several 750 ml bottles of varying vintages. A good choice for such a test would be a c chart.

Question 69

A painting contractor wishes to compare the work done by several painters in several rooms of varying sizes. If the contractor is concerned about drips and missed spots, an np chart would be the logical choice.

Question 70

The u chart is a graph of the number of defects per unit.

Question 71

The p chart is a process chart that is used to graph the proportion of items in a sample that are defective.

Question 72

Sensory attributes relate to whether or not a particular product or service performs as it is supposed to.

Question 73

Reliability models assume independence between failure events.

Question 74

The horizontal axis on the bathtub curve is reliability.

Question 75

When testing failure rate, there is no distinction as to whether hours of testing are continuous or performed at separate times.

Question 76

The vertical axis on the bathtub curve is failure rate.

Question 77

The lower control limit for a p chart cannot be lower than zero.

Question 78

An np chart can be used whether or not the sample sizes are the same.

Question 79

A defect is an irregularity or problem with a larger unit.

Question 80

The shape of the process line in a p chart and an np chart plot is always identical if the same data are used.