Question 1

Acceptance sampling

Accepted Answer

A) may involve inspectors taking random samples (or batches)of finished products and measuring them against predetermined standards. 
B) may involve inspectors taking random samples (or batches)of incoming raw materials and measuring them against predetermined standards. 
C) is more economical than 100% inspection. 
D) may be either of a variable or attribute type,although attribute inspection is more common in the business environment. 
E) All of the above are true. 
A) may involve inspectors taking random samples (or batches)of finished products and measuring them against predetermined standards. 
B) may involve inspectors taking random samples (or batches)of incoming raw materials and measuring them against predetermined standards. 
C) is more economical than 100% inspection. 
D) may be either of a variable or attribute type,although attribute inspection is more common in the business environment. 
E) All of the above are true.

Question 2

Ten samples of a process measuring the number of returns per 100 receipts were taken for a local retail store.The number of returns were 10,9,11,7,3,12,8,4,6,11.Find the standard deviation of the sampling distribution.(Hint- Use p-bar formula)

Accepted Answer

A) There is not enough information. 
B) .081 
C) 8.1 
D) .0273 
E) .0863 
A) There is not enough information. 
B) .081 
C) 8.1 
D) .0273 
E) .0863

Question 3

A   index greater than ________ is a capable process,one that generates fewer than 2.7 defects per 1000 at the ±3σ level.

Accepted Answer

The answer of A   index greater than ________...

Question 4

The purpose of an x-bar chart is to determine whether there has been a

Accepted Answer

A) change in the dispersion of the process output. 
B) change in the percent defective in a sample. 
C) change in the central tendency of the process output. 
D) change in the number of defects in a sample. 
E) change in the AOQ. 
A) change in the dispersion of the process output. 
B) change in the percent defective in a sample. 
C) change in the central tendency of the process output. 
D) change in the number of defects in a sample. 
E) change in the AOQ.

Question 5

Acceptance sampling

Accepted Answer

A) is the application of statistical techniques to the control of processes. 
B) was developed by Walter Shewhart of Bell Laboratories. 
C) is used to determine whether to accept or reject a lot of material based on the evaluation of a sample. 
D) separates the natural and assignable causes of variation. 
E) is based on standard deviations rather than range values. 
A) is the application of statistical techniques to the control of processes. 
B) was developed by Walter Shewhart of Bell Laboratories. 
C) is used to determine whether to accept or reject a lot of material based on the evaluation of a sample. 
D) separates the natural and assignable causes of variation. 
E) is based on standard deviations rather than range values.

Question 6

Assignable variation

Accepted Answer

A) is a sign that a process is under control. 
B) is to be identified and investigated. 
C) is the same as random variation. 
D) is variation that cannot be traced to a specific cause. 
E) leads to a steep OC curve. 
A) is a sign that a process is under control. 
B) is to be identified and investigated. 
C) is the same as random variation. 
D) is variation that cannot be traced to a specific cause. 
E) leads to a steep OC curve.

Question 7

The specification for a plastic liner for concrete highway projects calls for a thickness of 6.0 mm ± 0.1 mm.The standard deviation of the process is estimated to be 0.02 mm.What are the upper and lower specification limits for this product? The process is known to operate at a mean thickness of 6.03 mm.What is the   and   for this process? About what percent of all units of this liner will meet specifications?

Accepted Answer

LSL = 5.9 mm,USL = 6.1 mm. @#IMG-DLM& is (6.1 - 5.

Question 8

A local manufacturer supplies you with parts,and you would like to install a quality monitoring system at his factory for these parts.Historically,the defect rate for these parts has been 1.25% (You've observed this from your acceptance sampling procedures,which you would like to discontinue).Develop ± 3σ control limits for this process.Assume the sample size will be 200 items.

Accepted Answer

p-bar is 0.0125;the standard error of th

Question 9

Which of the following is true regarding the process capability index Cpk?

Accepted Answer

A) A Cpk index value of 1 is ideal,meaning all units meet specifications. 
B) The larger the Cpk,the more units meet specifications. 
C) The Cpk index can only be used when the process centerline is also the specification centerline. 
D) Positive values of the Cpk index are good;negative values are bad. 
E) The smaller the Cpk,the more units meet specifications. 
A) A Cpk index value of 1 is ideal,meaning all units meet specifications. 
B) The larger the Cpk,the more units meet specifications. 
C) The Cpk index can only be used when the process centerline is also the specification centerline. 
D) Positive values of the Cpk index are good;negative values are bad. 
E) The smaller the Cpk,the more units meet specifications.

Question 10

The number of late insurance claim payouts per 100 should be measured with a(n)

Accepted Answer

A) x-bar chart. 
B) R-chart. 
C) p-chart. 
D) c-chart. 
E) either a p or c chart. 
A) x-bar chart. 
B) R-chart. 
C) p-chart. 
D) c-chart. 
E) either a p or c chart.

Question 11

A process that is in statistical control will always yield products that meet their design specifications.

Accepted Answer

A) True 
 B)False

Question 12

In acceptance sampling,a manager can reach the wrong conclusion if the sample is not representative of the population it was drawn from.

Accepted Answer

A) True 
 B)False

Question 13

A manufacturer uses statistical process control to control the quality of the firm's products.Samples of 50 of Product A are taken,and a defective/acceptable decision is made on each unit sampled.For Product B,the number of flaws per unit is counted.What type(s)of control charts should be used?

Accepted Answer

A) p-charts for A and B 
B) p-chart for A,c-chart for B 
C) c-charts for both A and B 
D) p-chart for A,mean and range charts for B 
E) c-chart for A,mean and range charts for B 
A) p-charts for A and B 
B) p-chart for A,c-chart for B 
C) c-charts for both A and B 
D) p-chart for A,mean and range charts for B 
E) c-chart for A,mean and range charts for B

Question 14

X-bar charts are used when we are sampling attributes.

Accepted Answer

A) True 
 B)False

Question 15

What is the difference between natural and assignable causes of variation?

Accepted Answer

Natural variations are those variations

Question 16

A woodworker is concerned about the quality of the finished appearance of her work.In sampling units of a split-willow hand-woven basket,she has found the following number of finish defects in ten units sampled: 4,0,3,1,2,0,1,2,0,2.
a.Calculate the average number of defects per basket
b.If 3-sigma control limits are used,calculate the lower control limit,centerline,and upper control limit.

Accepted Answer

(a)1.5; (b

Question 17

An acceptance sampling plan must define "good lots" and "bad lots" and specify the risk level associated with each one.

Accepted Answer

A) True 
 B)False

Question 18

A manager wishes to build a 3-sigma range chart for a process.The sample size is five,the mean of sample means is 16.01,and the average range is 5.3.From Table S6.1 in the text,the appropriate value of   is 0,and   is 2.115.The UCL and LCL for this range chart are

Accepted Answer

A) 33.9 and 11.2. 
B) 33.9 and 0. 
C) 11.2 and 0. 
D) 6.3 and 0. 
E) 31.91 and 0.11. 
A) 33.9 and 11.2. 
B) 33.9 and 0. 
C) 11.2 and 0. 
D) 6.3 and 0. 
E) 31.91 and 0.11.

Question 19

The Central Limit Theorem states that when the sample size increases,the distribution of the sample means will approach the normal distribution.

Accepted Answer

A) True 
 B)False

Question 20

The mean and standard deviations for a process are μ = 90 and σ = 9.For the variable control chart,a sample size of 16 will be used.Calculate the standard deviation of the sampling distribution.

Accepted Answer

Sigma x-ba

Exam 18: Statistical Process Control

Acceptance sampling

Ten samples of a process measuring the number of returns per 100 receipts were taken for a local retail store.The number of returns were 10,9,11,7,3,12,8,4,6,11.Find the standard deviation of the sampling distribution.(Hint- Use p-bar formula)

A index greater than ________ is a capable process,one that generates fewer than 2.7 defects per 1000 at the ±3σ level.

The purpose of an x-bar chart is to determine whether there has been a

Acceptance sampling

Assignable variation

Which of the following is true regarding the process capability index Cpk?

The number of late insurance claim payouts per 100 should be measured with a(n)

A process that is in statistical control will always yield products that meet their design specifications.

In acceptance sampling,a manager can reach the wrong conclusion if the sample is not representative of the population it was drawn from.

A manufacturer uses statistical process control to control the quality of the firm's products.Samples of 50 of Product A are taken,and a defective/acceptable decision is made on each unit sampled.For Product B,the number of flaws per unit is counted.What type(s)of control charts should be used?

X-bar charts are used when we are sampling attributes.

What is the difference between natural and assignable causes of variation?

An acceptance sampling plan must define "good lots" and "bad lots" and specify the risk level associated with each one.

A manager wishes to build a 3-sigma range chart for a process.The sample size is five,the mean of sample means is 16.01,and the average range is 5.3.From Table S6.1 in the text,the appropriate value of is 0,and is 2.115.The UCL and LCL for this range chart are

The Central Limit Theorem states that when the sample size increases,the distribution of the sample means will approach the normal distribution.

The mean and standard deviations for a process are μ = 90 and σ = 9.For the variable control chart,a sample size of 16 will be used.Calculate the standard deviation of the sampling distribution.

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