This set of Industrial Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Acceptance Sampling”.
1. Sampling inspection is one of the scientific techniques of statistical quality control (SQC) used to control and evaluate the quality of process and products.
a) True
b) False
View Answer
Explanation: Based on the probability theory, statistical quality control (S.Q.C) evaluates as well as controls the quality of process and products. It has three scientific techniques, namely:
i. Sampling inspection
ii. Analysis of the data and
iii. Control charts
2. Which of the following are the drawbacks of acceptance sampling?
(i) Acceptance sampling is less expensive.
(ii) Acceptance sampling has the risk of accepting good lots and rejecting bad lots.
(iii) Acceptance sampling requires planning and documentation of the acceptance-sampling procedure whereas 100% inspection does not.
(iv) Acceptance sampling requires less manpower.
a) i, ii, iii, iv
b) ii, iii, iv
c) ii, iii
d) i, ii, iv
View Answer
Explanation: Acceptance sampling which is also known as lot-by-lot acceptance sampling has the disadvantage of accepting bad lots and rejecting good lots. Also, compared with other techniques it provides less information about the product or the process that manufactured the product. It also requires planning and documentation of the acceptance procedure which is not required in case of 100% inspection.
3. If the decision of accepting or rejecting a lot is done based on the inspection of a sample drawn from the same lot on which the decision has to be made, then such an inspection is known as ________
a) Centralised inspection
b) Sampling inspection
c) Endurance inspection
d) Pilot piece inspection
View Answer
Explanation: When a batch of components is to be inspected (say 1000), then a sample (say 10) is drawn from that lot or batch. This sample is inspected for defects. The decision of acceptance or rejection made on this sample will be reflected for the entire lot.
4. The groups are called as strata in __________
a) Stratified sampling
b) Cluster sampling
c) Multistage sampling
d) Simple random sampling
View Answer
Explanation: In stratified sampling, the population is divided into groups, based on one characteristic in which the groups are called strata.
5. _______ is an act of selecting sample pieces from the lot for the purpose of inspection at random.
a) Random Sampling
b) Convenience sampling
c) Stratified sampling
d) Clustered sampling
View Answer
Explanation: Random Sampling is an act of selecting sample pieces from the lot for the purpose of inspection at random. The sample pieces selected should represent the quality of the entire lot.
6. Calculate the sample size for a lot of 1000 components.
a) 40
b) 42
c) 44
d) 45
View Answer
Explanation:
Given,
N = lot size = 1000
Required to find sample size (n)
Generally, sample size can be determined from the SQC tables. But, it can also be determined using the following formula.
n = √(2N)
⇒ n = √(2 × 1000) = √(2000) = 44.72 ≡ 45.
7. Which of the following statements are true with regards to the selection of a sample size?
(i) The sample size (n) may be a fixed percentage of lot size (N).
(ii) The sample size (n) may be kept constant irrespective of lot size (N).
(iii) Sample size (n) can be selected at the personal whim of the inspector.
a) i only
b) i, ii only
c) i, ii, iii
d) i, iii only
View Answer
Explanation: The selection of sizes of N and n can be done in two ways.
I. The sample size (n) may be a fixed percentage of lot size (N).
II. The sample number (n) may be kept constant irrespective of lot size (N).
8. Calculate the sample size (n) for a lot of 200. Take the sample size as 5% of lot size.
a) 20
b) 22
c) 10
d) 15
View Answer
Explanation:
Given,
N = 200
Sample size (n) = 5% of lot size
Using fixed percentage method,
Sample size (n) = (5/100) × 200 = 10.
9. Acceptance number is the maximum allowable number of defectives articles in the sample.
a) True
b) False
View Answer
Explanation: Acceptance number is the maximum allowable number of defectives articles in the sample. It is denoted by the letter ‘C’. If the number of defectives in the sample is more than ‘C’, then the lot gets rejected else it is accepted.
10. In order to find a sample with zero defects, the acceptance number ‘C’ that has to be chosen is ______
a) C = 1
b) C = 0
c) C = 9
d) C = 3
View Answer
Explanation: Since acceptance number ‘C’ is the maximum number of defective articles that can be allowed in a given sample during the inspection, for a sample with zero defectives its number should be zero i.e., C = 0.
11. Find the average outgoing quality (AOQ) for a lot size of 200, sample size of 20, probability of acceptance (pa) is 0.5 and fraction defective (P) is 0.2.
a) 0.99
b) 0.019
c) 0.19
d) 0.09
View Answer
Explanation:
Given,
N = 200
n = 20
pa = 0.5
P = 0.2
AOQ = P = 0.5 × 0.2 × \(\frac {200 \, – \, 20}{200}\) = 0.09
Sanfoundry Global Education & Learning Series – Industrial Engineering.
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