Deck 10: B: Statistical Quality Control

Question 1

Acceptance sampling plans must specify the lot size,the sample size,and the acceptance/rejection criteria.

Answer 1

True

Question 2

The steeper an OC curve is,the less it tends to discriminate between good and bad lots.

Answer 2

False

Question 3

The terms "consumer's risk" and "alpha risk" both refer to a Type I error.

Answer 3

False

Question 4

Inspection both before and after production involves acceptance sampling procedures.

Question 5

In a double-sampling plan,a second sample is taken if the results of the first sample are inconclusive.

Question 6

The ability of an acceptance sampling plan to discriminate between good and bad quality lots is described by its operating characteristic curve.

Question 7

The purpose of acceptance sampling is to decide whether a batch of items satisfies predetermined standards.

Question 8

Acceptance sampling is a form of inspection applied to items that are part of an ongoing process.

Question 9

Acceptance sampling is most useful when the cost consequences of passing defectives are low.

Question 10

Acceptance sampling procedures can be applied to both attribute and variable inspection.

Question 11

If a lot,or batch,is "rejected" during acceptance sampling,the lot will usually be thrown away.

Question 12

Acceptance sampling is applied to batches of items during the production process.

Question 13

In a single-sampling plan,the entire lot,or batch of items,is accepted or rejected based upon only one specified sized sample.

Question 14

The AQL is associated with a producer's risk.

Question 15

The average outgoing quality (AOQ)assumes that lots contain some given proportion defective.

Question 16

In a double-sampling plan,a second sample may not be taken if the results of the first sample are conclusive.

Question 17

A double-sampling plan always requires a second sample.

Question 18

The LTPD is associated with a consumer's risk.

Question 19

Inspection that occurs during the production process is known as acceptance sampling.

Question 20

The cost and time required for inspection dictate the type of sampling plan used.

Question 21

A Type II (beta)error occurs when:

A) a bad lot is accepted.
B) a good lot is rejected.
C) a bad lot is rejected.
D) a good lot is accepted.
E) none of the choices.

Question 22

Sampling plans typically specify:

A) lot size.
B) sample size.
C) number of samples to be taken.
D) acceptance/rejection criteria.
E) sample size, number of samples to be taken, and acceptance/rejection criteria.

Question 23

In acceptance sampling,the level of inspection automatically adjusts to the quality of lots being inspected,assuming that:

A) a single-sampling plan is used.
B) double-sampling plans are used.
C) multiple-sampling plans are used.
D) "rejected" lots are subjected to 100 percent inspection.
E) none of the choices.

Question 24

"Average outgoing quality" will show the average quality level of inspected and uninspected lots for any given incoming proportion defective.

Question 25

A lot can be "accepted" or "rejected" in a multiple-sampling plan:
I)after one sample is checked multiple times.
II)after two samples are taken.
III)after one or more samples are taken.

A) I only
B) II only
C) III only
D) I or II
E) I or III

Question 26

A Quality Inspector for Alpha-Beta Co.is concerned about the quality of the batch of several thousand Gizmos which his company produced this week and is preparing to ship.If the cost of replacing a defective Gizmo once it has been shipped is $2.00,while the cost of 100% inspection prior to shipment is $.40 each,at what point is he indifferent between 100% inspection or shipment without inspection?

A) 0% defectives
B) 2% defectives
C) 5% defectives
D) 20% defectives
E) 30% defectives

Question 27

Which one of the following would not be a reason for using acceptance sampling?

A) High cost of passing defectives
B) Large number of items
C) Destructive testing
D) Boredom and fatigue that would accompany complete inspection
E) All of the choices are reasons.

Question 28

A Quality Inspector for Alpha-Beta Co.is concerned about the quality of the batch of several thousand Gizmos which his company produced this week and is preparing to ship.If he uses an acceptance sampling plan of n = 5 and c = 2,what will be the average outgoing quality (AOQ)for batches with 40% defectives?

A) 0.1270
B) 0.2730
C) 0.3174
D) 0.6826
E) 0.7270

Question 29

The AQL indicates:

A) acceptable quality level.
B) average quality level.
C) actual quality level.
D) aggregate quality level.
E) approximate quality level.

Question 30

Acceptance sampling plans might call for selection of:

A) a single sample.
B) two samples.
C) several samples.
D) all of the choices.
E) none of the choices.

Question 31

The AOQ shows:

A) the maximum quality.
B) how well a sampling plan can discriminate between good and bad lots.
C) the actual quality level.
D) "good" quality.
E) none of the choices.

Question 32

The Quality Manager for Graphics,Inc.is concerned about the quality of the lot of several thousand posters which her company printed this week and is now preparing to ship.If the cost of replacing a defective poster once it has been shipped is $10.00,while the cost of complete 100% inspection prior to shipment is $.50 per poster,at what point is she indifferent between complete inspection or shipment without inspection?

A) 5%
B) 10%
C) 12%
D) 20%
E) 25%

Question 33

The Quality Manager for Graphics,Inc.is concerned about the quality of the lot of several thousand posters which her company printed this week and is now preparing to ship.If,based on her acceptance sample,she decides to ship this lot without inspection,which type error would be possible?

A) Type I
B) Type II
C) Both Type I and Type II error
D) Neither Type I nor Type II error
E) Cannot be determined exactly

Question 34

A Type I (alpha)error occurs when:

A) a bad lot is accepted.
B) a good lot is rejected.
C) a bad lot is rejected.
D) a good lot is accepted.
E) none of the choices.

Question 35

The ability of a sampling plan to discriminate between lots of high quality and lots of low quality is described by:

A) a Gantt chart.
B) an operating characteristic curve.
C) an average outgoing quality curve.
D) a process control chart.
E) a range chart.

Question 36

A Quality Inspector for Alpha-Beta Co.is concerned about the quality of the batch of several thousand Gizmos which his company produced this week and is preparing to ship.If he uses an acceptance sampling plan of n = 5 and c = 2,what is the probability that,if this batch is 40% defective,it will be rejected and receive 100% inspection prior to shipment?

A) 0.1270
B) 0.2730
C) 0.3174
D) 0.6826
E) 0.7270

Question 37

A Quality Inspector for Alpha-Beta Co.is concerned about the quality of the batch of several thousand Gizmos which his company produced this week and is preparing to ship.If,based on his acceptance sample,he decides to ship this batch without inspection,which type of error would be possible?

A) None would be possible
B) Producer's error
C) Type I error
D) Type II error
E) Both Type I and Type II error

Question 38

A lot can be "accepted" or "rejected" in a double-sampling plan:
I)after one sample is taken.
II)after two samples are taken.
III)after one sample is checked twice.

A) I only
B) II only
C) III only
D) I or II
E) I or III

Question 39

The purpose of acceptance sampling is to:

A) estimate process quality.
B) estimate lot quality.
C) detect and eliminate defectives.
D) decide if a lot meets predetermined standards.
E) accept samples of products.

Question 40

An OC curve shows:

A) average outgoing quality.
B) the average outgoing quality limit.
C) out of control criteria.
D) operating control.
E) probability of acceptance versus lot quality.

Question 41

The Quality Manager for Microelectronics,Inc.is concerned about the quality of the batch of several thousand IC's (integrated circuits)which his company is about to ship.If the cost of replacing a defective IC once it has been shipped is $5.00,while the cost of complete (100%)inspection prior to shipment is $.20 each,at what point is he indifferent between complete inspection or shipment without inspection?

A) 0% defectives
B) 4% defectives
C) 5% defectives
D) 9% defectives
E) 22% defectives

Question 42

The Quality Manager for Graphics,Inc.is concerned about the quality of the lot of several thousand posters which her company printed this week and is now preparing to ship.If she uses an acceptance sampling plan of n = 10 and c = 2,what will be the average outgoing quality (AOQ)for lots with 20% defectives?

A) 0.13556
B) 0.20000
C) 0.23630
D) 0.58434
E) 0.32484

Question 43

Given the following acceptance sampling data for a lot of several thousand units of a finished good:
If c = 2,what is the probability that,if this lot were 5% defective,it would be rejected and completely inspected prior to shipment?
10% defective?
15%?
20%?

Question 44

Shipments of bowling balls are sampled before delivery to a warehouse.Lots of 600 balls are checked,using 10 observations from each lot.Any lot with more than one defective is rejected.Calculate values for the operating characteristic curve for this sampling plan.

Question 45

The Quality Manager for Widgets,Inc.is concerned about the quality of the lot of several thousand widgets which his company produced this week and is now ready to ship.If he uses an acceptance sampling plan of n = 8 and c = 1,what will be the average outgoing quality (AOQ)for lots with 10% defectives?

A) .0813
B) .0962
C) .1869
D) .7318
E) .8131

Question 46

A firm that makes plastic wrapping material takes random samples of 50 items from each lot before it is sent to a customer.Lots contain 2,000 items each.Any lot with more than one defective is subjected to 100 percent inspection,and any defectives are replaced with good ones.
(i)Construct the OC curve for this plan.
(ii)Construct the AOQ curve for this plan.What is the approximate AOQ limit?

Question 47

The Quality Manager for Microelectronics,Inc.is concerned about the quality of the batch of several thousand IC's (integrated circuits)which his company is about to ship.If he uses an acceptance sampling plan of n = 20 and c = 1,what is the probability that,if this batch is 15% defectives,it will be rejected and completely inspected prior to shipment?

A) 0.0263
B) 0.1237
C) 0.1756
D) 0.8244
E) 0.9737

Question 48

The Quality Manager for Widgets,Inc.is concerned about the quality of the lot of several thousand widgets which his company produced this week and is now ready to ship.If he uses an acceptance sampling plan of n = 8 and c = 1,what is the probability that,if this lot is 10% defective,it will be accepted for shipment without inspection?

A) .9619
B) .9428
C) .8131
D) .4305
E) .1869

Question 49

The Quality Manager for Graphics,Inc.is concerned about the quality of the lot of several thousand posters which her company printed this week and is now preparing to ship.If the indifference point between complete inspection or shipment without inspection is 12% defectives,and she decides to sample 15 posters (n = 15),what is the maximum number of sample defectives (c)for which this lot would be accepted for shipment without further inspection?

A) 0 defectives
B) 1 defective
C) 2 defectives
D) 3 defectives
E) 4 defectives

Question 50

The Quality Manager for Graphics,Inc.is concerned about the quality of the lot of several thousand posters which her company printed this week and is now preparing to ship.If she uses an acceptance sampling plan of n = 10 and c = 2,what is the probability that,if this lot is 10% defective,it will be accepted for shipment without inspection?

A) 0.9298
B) 0.0702
C) 0.8189
D) 0.2198
E) 0.5995

Question 51

Given the following acceptance sampling data for a lot of several thousand units of a finished good:
If c = 2,what is the probability that,if this lot were 5% defective,it would be accepted for shipment without inspection?
10% defective?
15%?
20%?

Question 52

Given the following acceptance sampling data for a lot of several thousand units of a finished good:
If this lot were 5% defective,what type error would be possible?
For an acceptance sampling plan with c = 2,what would be the risk of this error?

Question 53

The Quality Manager for Microelectronics,Inc.is concerned about the quality of the batch of several thousand IC's (integrated circuits)which his company is about to ship.If,based on his acceptance sample,he decides to ship this batch without inspection,which type error would be possible?

A) None would be possible
B) Producer's error
C) Type I error
D) Type II error
E) Both Type I and Type II error

Question 54

The Quality Manager for Widgets,Inc.is concerned about the quality of the lot of several thousand widgets which his company produced this week and is now ready to ship.If he uses an acceptance sampling plan of n = 8 and c = 1,what is the probability that,if this lot is 15% defective,it will be rejected and completely inspected prior to shipment?

A) .8948
B) .8131
C) .6572
D) .5033
E) .3428

Question 55

The Quality Manager for Microelectronics,Inc.is concerned about the quality of the batch of several thousand IC's (integrated circuits)which his company is about to ship.If the indifference point between complete inspection and shipment without inspection is 9% defectives,and he decides to sample 40 IC's (n = 40),what is the maximum number of sample defectives (c)for which this batch would be accepted for shipment without inspection?

A) 0 defectives
B) 1 defective
C) 2 defectives
D) 3 defectives
E) 4 defectives

Question 56

The Quality Manager for Microelectronics,Inc.is concerned about the quality of the batch of several thousand IC's (integrated circuits)which his company is about to ship.If he uses an acceptance sampling plan of n = 20 and c = 1,what will be the average outgoing quality (AOQ)for batches with 15% defectives?

A) 0.0263
B) 0.1237
C) 0.1756
D) 0.8244
E) 0.9737

Question 57

The Quality Manager for Widgets,Inc.is concerned about the quality of the lot of several thousand widgets which his company produced this week and is now ready to ship.If the cost of replacing a defective widget once it has been shipped is $5.00,while the cost of complete (100%)inspection prior to shipment is 30 cents per widget,what is the point of indifference between complete inspection and shipment without inspection?

A) 1.67% defectives
B) 3% defectives
C) 5% defectives
D) 6% defectives
E) 16.7% defectives

Question 58

A manufacturer purchases large quantities of metal brackets from several suppliers.The brackets are shipped in lots of 8,000 each.Random samples of 40 brackets are taken from each lot,and the lot is rejected if any defectives are discovered.Rejected lots are subjected to 100 percent inspection,and any defectives are replaced with good brackets.Determine the average outgoing quality limit for this sampling plan.

Question 59

Given the following acceptance sampling data for a lot of several thousand units of a finished good:
What is the point of indifference between 100 percent inspection or shipment without inspection?

Question 60

Given the following acceptance sampling data for a lot of several thousand units of a finished good:
If this lot were 20% defective,what type error would be possible?
For an acceptance sampling plan with c = 2,what would be the risk of this error?

Question 61

Given the following acceptance sampling data for a lot of several thousand units of a finished good:
For an acceptance sampling plan with c = 2,what will be the average outgoing quality for lots with 5% defectives?
10%?
15%?
20%?