Question 1
A type II error is also called a ___________
A. α Error
B. δ Error
C. β Error
D. ∅ Error
View Answer
Answer: Option C
Explanation:
A type II error is concluding a process in-control when it is actually in out-of-control state. A type II error is also called an β error.
Question 2
An OC curve is a display of ___________
A. β Error against defectives in a process output over a limited period of time
B. β Error against time
C. β Error against the process fraction nonconforming
D. Fraction nonconforming against β Error
View Answer
Answer: Option C
Explanation:
An OC curve or Operation characteristic curve for a p-chart is a graphical representation of β Error against the process fraction nonconforming computed.
Question 3
Defectives word has almost same meaning as __________
A. Conforming
B. Nonconforming
C. Non-defective
D. Un-conforming
View Answer
Answer: Option B
Explanation:
A nonconforming item is an item which does not conform to the specifications defined for its quality characteristics. A defective is having almost same as the nonconforming item.
Question 4
Even if 100% inspection is done, control chart can have a variable sample size.
A. TRUE
B. FALSE
View Answer
Answer: Option A
Explanation:
In some applications of the p-chart, the sample is 100% inspection of process output over a time period. Since different number of units could be produced in each period, the control chart would then have a variable sample size.
Question 5
Even if the process is in control according to p-chart and the fraction nonconforming is too high, it states that _________
A. The process is not stable
B. The process is stable but there are no operator controllable problems
C. The process is stable but there are some operator controllable problems
D. The process is out of control
View Answer
Answer: Option B
Explanation:
If the process is in control according to p chart but the fraction nonconforming is too high, it states that the process is stable with no operator controllable problems.
Question 6
For a control chart data having the average sample fraction nonconforming= 0.2313 and the sample size=50, what will be the value of the UCL for the np control chart?
A. 2.62
B. 20.51
C. 11.56
D. 11.892
View Answer
Answer: Option B
Explanation:
We know that for a np chart,UCL=\(n\bar{p}+3\sqrt{n\bar{p} (1-\bar{p})}\) Putting the values, we get, UCL=20.51.
Question 7
For narrower limits of control, which of this is true?
A. Chart becomes insensitive to small shift
B. Chart becomes more sensitive to small shift but gives false alarms
C. Chart becomes more sensitive to small shift but gives accurate alarms
D. Chart gives no alarms at all
View Answer
Answer: Option B
Explanation:
If the narrower limits like 1-sigma limits or 2 – sigma limits are chosen for p-chart, the chart becomes more sensitive to small shifts. But in addition, it also gives more numbers of false alarms.
Question 8
For what value of sample size, will the p-chart will have a LCL value higher than 0 when p=0.05 and 3 sigma limits are used?
A. n>121
B. n>100
C. n>125
D. n>171
View Answer
Answer: Option D
Explanation:
We know for a p chart having LCL value higher than zero, we have,\(n>\frac{1-p}{p}*L^2 \) For p=0.05 and L=3, we get, n>171.
Question 9
If the for a fraction nonconforming chart, the probability of a sample point plotting out of control is 0.0531, what will be the ARL for this?
A. 12.31
B. 8.16
C. 18.83
D. 22.78
View Answer
Answer: Option C
Explanation:
The fraction nonconforming chart which has the probability of a sample point plotting out of control as p, the ARL is given by,ARL = 1⁄pPutting p=0.0531, ARL=18.83.
Question 10
If the fraction nonconforming for 7 samples are 0.11,0.24,0.21,0.14,0.24,0.21,0.17, what is the value for the center line for a p-chart?
A. 0.19
B. 0.21
C. 0.12
D. 0.13
View Answer
Answer: Option A
Explanation:
The center line of a p chart represents the average of the all the fraction nonconforming. This means,\(CL=\bar{p}=\frac{\sum_{i=0}^n p_i}{n}\) This gives, CL=0.19 for the above question.
Question 11
If the p=0.2313 for a np chart, and the number of items in a sample are 50, what will be the center line value of the np chart?
A. 10.34
B. 11.56
C. 10.11
D. 13.21
View Answer
Answer: Option B
Explanation:
The center line of the np chart represents the value equal to,CL=npHere, n=50 and p=0.2313, putting these values in the CL value, we get, CL=11.565.
Question 12
If the sample size for a p-chart is 50 and the value for the center line of the chart is 0.2313, what will be the value of the LCL of the chart?
A. 0.4108
B. 0.0524
C. 0.0762
D. 0.0389
View Answer
Answer: Option B
Explanation:
The LCL of the p chart is given by expression,LCL=\(p-\sqrt{\frac{p(1-p)}{n}}\) When we put the value of CL=p=0.2313, we get LCL=0.0524.
Question 13
If there are 9 items defective in the sample size of 28, what will be the value that the fraction nonconforming chart, will represent?
A. 0.2971
B. 0.3214
C. 0.6328
D. 0.8172
View Answer
Answer: Option B
Explanation:
The fraction nonconforming chart center line when standards are given, represents the value of fraction nonconforming which in this case, where m=1, D=9, n=28, is,\(\bar{p}=\frac{[∑_{i=1}^m D_i]}{mn}=\frac{9}{28}\)=0.3214
Question 14
If type II error probability for a process is 0.8594, its ARL will be ____
A. 8
B. 1
C. 3
D. 7
View Answer
Answer: Option D
Explanation:
We know,\(ARL_1=\frac{1}{1-β}\) We have, β=0.8594, so ARL1≅7
Question 15
In the p-chart, even if only one point is out of control, we should conclude that the process is out-of-control.
A. TRUE
B. FALSE
View Answer
Answer: Option B
Explanation:
It is generally not an intelligent decision to conclude the process state as out-of-control by obtaining only one point out of control in p-chart; since for any p>0, there is a probability of producing some defectives.
Question 16
Non-defective term has the same meaning as Nonconforming.
A. TRUE
B. FALSE
View Answer
Answer: Option B
Explanation:
Non-defective product means a product, which is not defective, or which conforms to specifications defined for it. A nonconforming product does not conform to the specifications defined for it.
Question 17
The c charts are also called _________
A. The control chart for nonconformities
B. Control charts for fraction nonconforming
C. Control charts for conformities per unit
D. Control chart for process mean
View Answer
Answer: Option A
Explanation:
The control charts which are made for the analysis of the defects in a product, are generally called the control charts for fraction nonconforming, or c charts.
Question 18
The center line of control chart of fraction nonconforming represents the value equal to ____________
A. Fraction nonconforming
B. Process mean
C. Process standard deviation
D. Sample mean
View Answer
Answer: Option A
Explanation:
The center line of the control chart of fraction nonconforming represents the value equal to the fraction nonconforming, i.e. the ratio between the number of nonconforming units to the total sample size.
Question 19
The center line of the np-control chart represents the value equal to ____________
A. p
B. p
C. np
D. 1-np
View Answer
Answer: Option C
Explanation:
The center line of the np chart or the number nonconforming chart represents the value equal to np or np.
Question 20
The control chart designed to deal with the defects or nonconformities of a product, is called __________
A. p chart
B. c chart
C. R chart
D. s chart
View Answer
Answer: Option B
Explanation:
In some situations, it is more convenient to deal with the no of defects rather than the fraction nonconforming. The control charts designed for this purpose are called the c charts.
Question 21
The control chart which relates to the fraction of defective product produced by a manufacturing process, is called _________
A. The control chart for nonconformities
B. Control charts for fraction nonconforming
C. Control charts for conformities per unit
D. Control chart for process mean
View Answer
Answer: Option B
Explanation:
The control charts which are related to the fraction of nonconforming or defective product produced by a manufacturing process is called the control chart for fraction nonconforming.
Question 22
The control charts used for the analysis of nonconformities per unit of a product, are called _________ charts
A. p
B. c
C. x
D. u
View Answer
Answer: Option D
Explanation:
The control charts useful in the situations where the average number of defects or conformities per unit, is more convenient basis for process control; are called the u charts.
Question 23
The control limits for p-chart found from the use of estimated unknown fraction non conforming, are regarded as __________
A. Final limits
B. Concluded limits
C. Trial limits
D. Absolute limits
View Answer
Answer: Option C
Explanation:
The control limits for p chart, which are not found using the standard values of p, are generally regarded as trial limits. The finalized limits are calculated by first implementing the trial limits.
Question 24
The fraction nonconforming says the same thing as the term defects per unit.
A. TRUE
B. FALSE
View Answer
Answer: Option B
Explanation:
Fraction nonconforming is the ratio of the number of defectives in a sample to its sample size. “Defects per unit” counts the defects in a single unit.
Question 25
The gap between the UCL and LCL is double the gap between either one of them and the Center line, for the standardized chart.
A. TRUE
B. FALSE
View Answer
Answer: Option A
Explanation:
The Center line for standardized chart is at 0, and UCL and LCL for standardized chart are at ±3 respectively. So the gap between the UCL and LCL is 6, which is double the gap between the gap between either, one of them and the center line, which is 3 units.
Question 26
The number nonconforming chart is also called ___________
A. np-chart
B. p-chart
C. c-chart
D. s-chart
View Answer
Answer: Option A
Explanation:
The number nonconforming chart is also called the np-chart. This uses the number of nonconforming items in a sample instead of the fraction nonconforming.
Question 27
The points plotting below the lower control limit of p-chart do not always represent the out-of-control process or an assignable cause.
A. TRUE
B. FALSE
View Answer
Answer: Option A
Explanation:
The point can be plotted below the LCL of p-chart because of errors in inspection process resulting from inadequately trained or inexperienced inspectors. Sometimes, inspectors pass deliberately the nonconforming units too.
Question 28
The ratio of the number of nonconforming items in a population to total number of items in that population, is called _________
A. Fraction nonconforming
B. Fraction of nonconformities
C. Fraction of conformities per unit of product
D. Fraction of variability
View Answer
Answer: Option A
Explanation:
The fraction nonconforming is delineated by the ratio of nonconforming items in a population to the total number of items in the population.
Question 29
The standardized control chart has the center line at ____________
A. 1 σ
B. 2 σ
C. Zero
D. -1σ
View Answer
Answer: Option C
Explanation:
The standardized control chart used for control charts for fraction nonconforming with variable sample size, has its center line at the value zero.
Question 30
The u charts are also called _________
A. The control chart for nonconformities
B. Control charts for fraction nonconforming
C. Control charts for conformities per unit
D. Control chart for process mean
View Answer
Answer: Option C
Explanation:
The control charts plotted for the conformities per unit are called u charts. They are helpful in the situations where average number of defectives is very important to determine process state.
Question 31
The value of L=3 in the genera model of control limits for a Shewhart control chart, explains ____________
A. There are 3 sigma limits taken
B. There are 3 quality characteristics
C. There are 6 quality characteristics
D. There are 6 sigma limits taken
View Answer
Answer: Option A
Explanation:
The value of L=3 in the general model of control limits for a Shewhart control chart signifies that there are 3 sigma limits taken, i.e. the 3 times shift of the standard deviation, of the mean will be measured on either side.
Question 32
To deal with the variable sample size, the standardized chart is used, which has its upper limit at ___________
A. 3
B. -3
C. 1
D. 0
View Answer
Answer: Option A
Explanation:
The standardized control chart, which has been used over quite some time to handle the situations of variable sample size, has its upper limit at +3.
Question 33
Variable control charts can also be applied on attributes but their efficiency will be less as compared to the attribute control charts.
A. TRUE
B. FALSE
View Answer
Answer: Option B
Explanation:
Variables are incremented on a continuous scale whereas, attributes do not increment on a continuous scale. Attribute data is about conformity or nonconformity of a sample. As variable charts cannot be used for conforming and nonconforming data, they are not applied on attributes data.
Question 34
We cannot analyze abnormal runs or patterns directly, on p-chart with variable sample size.
A. TRUE
B. FALSE
View Answer
Answer: Option A
Explanation:
We cannot analyze abnormal runs or patterns directly on p chart with variable sample size. It’s because, the sample nonconforming data can indicate poorer quality for a sample with less defects or variability.
Question 35
What is done when there is a sample plotted out of control limits for a p-chart?
A. The sample is investigated for an assignable cause and then the sample data is eliminated to develop a new p-chart
B. The sample is only investigated for an assignable cause
C. The sample is not investigated at all (It is assumed that there was no assignable cause present)
D. All the samples are investigated
View Answer
Answer: Option A
Explanation:
When a sample plots out of control in p-chart, it is investigated for an assignable cause and then the sample data is eliminated to develop a new p-chart.
Question 36
When the Lower control limits for a p chart are less than zero, what is done?
A. The value LCL<0 is utilized in control chart
B. There is a certain constant C added to both UCL and LCL, i.e. UCLnew=UCLold+ C and LCLnew=LCLold+C
C. There is certain constant value added to LCL only, i.e. LCLnew=LCLold+C
D. LCL=0 is taken and assumed that control chart only has the upper control limit
View Answer
Answer: Option D
Explanation:
The value of LCL is taken to be zero when there is a value less than 0 found for LCL. It is also assumed that the control chart only has the upper control limit.
Question 37
Which of these gives a correct equation for the general model for Shewhart control chart for a “w” quality characteristic statistic?
A. UCL = μw + Lσw
B. UCL = μw – Lσw
C. LCL = μw + Lσw
D. LCL = μw + σw
View Answer
Answer: Option A
Explanation:
The Upper control limit for constructing a Shewhart control chart for a quality characteristic w, we have;UCL = μw + Lσw.
Question 38
Which of these is not one of the parameters which need to be specified for fraction nonconforming control charts?
A. Sample Size
B. Frequency of sampling
C. Width of control limits
D. Units to be produced
View Answer
Answer: Option D
Explanation:
the fraction nonconforming chart has 3 parameters which need to be specified: the sample size, the frequency of sampling, and the width of control limits.
Question 39
Which one of these is not a method to plot the variable sample size data on p-chart?
A. Variable-width control limits
B. Control limits based on average sample size
C. Tolerance diagram
D. Standardized Control Chart
View Answer
Answer: Option C
Explanation:
The three approaches to deal with variable sample size are: variable-width control limits, control limits based on average sample size, and standardized control chart.