Chapter 10S – Acceptance Sampling
36. 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.
(A) Construct the OC curve for this plan.
(B) Construct the AOQ curve for this plan. What is the approximate AOQ limit?
Chapter 10S – Acceptance Sampling
37. 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.
Chapter 10S – Acceptance Sampling
A Quality Inspector for Alpha-Beta Co. is concerned about the quality of the batch of several
thousand blank DVD disks which his company produced this week and is preparing to ship.
38. If the cost of replacing a defective DVD disk 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 and shipment without inspection?
39. 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?
Chapter 10S – Acceptance Sampling
10S-19
40. 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?
41. If, based on his acceptance sample, he decides to ship this batch without inspection, which
type error would be possible?
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.
Chapter 10S – Acceptance Sampling
42. 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 and shipment without inspection?
43. 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?
Chapter 10S – Acceptance Sampling
44. 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?
45. If, based on her acceptance sample, she decides to ship this lot without inspection, which
type error would be possible?
Chapter 10S – Acceptance Sampling
46. If the indifference point between complete inspection and 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?
The Quality Manager for Frozen Pizzas, Inc. is concerned about the quality of the lot of
several thousand pizzas which his company produced this week, and is now ready to ship.
47. If the cost of replacing a defective pizza once it has been shipped is $5.00, while the cost
of complete (100%) inspection prior to shipment is 30 cents per pizza, what is the point of
indifference between complete inspection and shipment without inspection?
Chapter 10S – Acceptance Sampling
48. 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?
49. 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?
Chapter 10S – Acceptance Sampling
50. 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?
The Quality Manager for Microelectronics, Inc. is concerned about the quality of the batch of
several thousand Z-box games which his company is about to ship.
51. If the cost of replacing a defective Z-box game 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 and shipment without inspection?
Chapter 10S – Acceptance Sampling
52. 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?
53. 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?
Chapter 10S – Acceptance Sampling
54. If, based on his acceptance sample, he decides to ship this batch without inspection, which
type error would be possible?
Given the following acceptance sampling data for a lot of several thousand units of a finished
good:
Per-unit cost of replacing a defective unit after it has been shipped is $5.00
Per-unit cost of 100% inspection prior to shipment is $.60
55. What is the point of indifference between 100 percent inspection and shipment without
inspection?
Chapter 10S – Acceptance Sampling
56. If n = 20 and 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%?
57. If n = 20 and 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%?
58. 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?
Chapter 10S – Acceptance Sampling
59. 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?
60. For an acceptance sampling plan with c = 2, what will be the average outgoing quality for
lots with 5% defectives? 10%? 15%? 20%?
61. A firm uses acceptance sampling to evaluate batches of inputs. Ideally, the defect rate
would be no more than 3.5%. The firm knows that on occasion, batches with higher defect
rates will be accepted. However, if the defect rate reaches 7%, the firm would like there to be
very little chance of that batch being accepted. This value, 7%, is the firm’s ______.
Chapter 10S – Acceptance Sampling
62. A firm uses acceptance sampling to evaluate batches of inputs. Ideally, the defect rate
would be no more than 3.5%. The firm knows that on occasion, batches with that defect rate
or better might be rejected. However, if the defect rate is less than or equal to 3.5%, the firm
would like there to be very little chance of that batch being rejected. This value, 3.5%, is the
firm’s ______.
63. Suppose a batch is of acceptable quality. There’s a 10% chance that it will be rejected.
Thus, ________ is 10%.
64. Suppose a batch is of unacceptable quality. There’s a 10% chance that it will be accepted.
Thus, ________ is 10%.
Chapter 10S – Acceptance Sampling
65. If the value for Average Outgoing Quality increases, this means that __________
defective units are being passed on.