Question 1

You are developing an X-bar chart based on sample means. You know the standard deviation of the sample means is 4, the desired confidence level is 99 percent, and the average of the sample means is 20. Which of the following is your LCL?

Accepted Answer

A)   36
B)   24
C)   9.68
D)   16.79
E)   30.32

Question 2

If the fraction defective is 0.4 based on a sample size of 100, the standard deviation used in the p-chart is about 0.10.

Accepted Answer

A) True 
 B)False

Question 3

Variation that is inherent in a production process itself is called assignable variation.

Accepted Answer

A) True 
 B)False

Question 4

The producer's risk associated with rejecting a high-quality lot is denoted in acceptance sampling with the Greek letter beta.

Accepted Answer

A) True 
 B)False

Question 5

Quality control charts usually have a central line and upper and lower control limit lines. Which of the following is not a reason that the process being monitored with the chart should be investigated?

Accepted Answer

A)   A large number of plots are close to the upper or lower control lines.
B)   The behavior of the plots is erratic.
C)   A single point falls above or below the control limits.
D)   There is a change in raw materials or operators.
E)   There is a run of five above the central line.

Question 6

Process control is concerned with monitoring quality after the product or service has been produced.

Accepted Answer

A) True 
 B)False

Question 7

You have just used the capability index (Cpk)  formulas to compute the two values "min [1.5, 1]." Which of the following is the proper interpretation of these numbers?

Accepted Answer

A)   The true capability index value is 1.
B)   The mean of the production process has shifted to the left of the design limits.
C)   The mean of the production process has shifted to the right of the design limits.
D)   The mean has not shifted at all.
E)   The true capability index value is between 1.5 and 1.

Question 8

The capability index (Cpk) indicates the position of the mean and tails of a process's variance relative to design specifications.

Accepted Answer

A) True 
 B)False

Question 9

An example of assignable variation in a production system may be that workers are not identically trained.

Accepted Answer

A) True 
 B)False

Question 10

You are going to develop an R-chart based on range statistics, and you are using a sample size of 9 for your charting purposes. Which of the following is the lower control limit D3 factor for the chart?

Accepted Answer

A)   0.08
B)   0.14
C)   0.18
D)   0.22
E)   0.29

Question 11

One hundred percent inspection is justified when the cost of inspection is low.

Accepted Answer

A) True 
 B)False

Question 12

The p-chart is only useful for sampling that deals with continuous variables.

Accepted Answer

A) True 
 B)False

Question 13

It is impossible to have zero variability in production processes.

Accepted Answer

A) True 
 B)False

Question 14

If there are 40 total defects from 8 samples, each sample consisting of 200 individual items in a production process, which of the following is the fraction defective that can be used in a p-chart for quality control purposes?

Accepted Answer

A)   2.5
B)   0.25
C)   0.025
D)   0.0025
E)   0.00025

Question 15

Variation that is inherent in a production process itself is called common variation.

Accepted Answer

A) True 
 B)False

Question 16

In sampling variables, the actual measurements of the variable observed are used regardless of whether the unit is good or bad.

Accepted Answer

A) True 
 B)False

Question 17

You want to determine the control lines for a p-chart for quality control purposes. If the desired confidence level is 99 percent, which of the following values for "z" would you use in computing the UCL and LCL?

Accepted Answer

A)   0.99
B)   2
C)   2.58
D)   3
E)   None of these choices are correct.

Question 18

In monitoring process quality, we might use which of the following statistics?

Accepted Answer

A)   Absolute values
B)   Percentage deviation from tolerance centers
C)   "k" values for the sample mean
D)   Logarithmic control intervals
E)   Difference between the highest and lowest value in a sample

Question 19

For which of the following should we use an R-chart to monitor process quality?

Accepted Answer

A)   Weighing trucks at a highway inspection station to determine if they are overloaded
B)   Deciding whether an airliner has sufficient fuel for its trip
C)   Student grades measured from 1 to 100
D)   Determining whether vehicles from a motor pool will run
E)   Determining the accuracy of a forecast of "snow"

Question 20

Attributes are those quality characteristics that are classified as either conforming or not conforming to specification.

Accepted Answer

A) True 
 B)False

Exam 13: Statistical Quality Control

In sampling variables, the actual measurements of the variable observed are used regardless of whether the unit is good or bad.

Correct AnswerverifiedShow Answer

Variation that is inherent in a production process itself is called assignable variation.

Correct AnswerverifiedShow Answer

You want to determine the control lines for a p-chart for quality control purposes. If the desired confidence level is 99 percent, which of the following values for "z" would you use in computing the UCL and LCL?

Correct AnswerverifiedShow Answer

You are going to develop an R-chart based on range statistics, and you are using a sample size of 9 for your charting purposes. Which of the following is the lower control limit D3 factor for the chart?

Correct AnswerverifiedShow Answer

You are developing an X-bar chart based on sample means. You know the standard deviation of the sample means is 4, the desired confidence level is 99 percent, and the average of the sample means is 20. Which of the following is your LCL?

Correct AnswerverifiedShow Answer

Variation that is inherent in a production process itself is called common variation.

Correct AnswerverifiedShow Answer

Process control is concerned with monitoring quality after the product or service has been produced.

Correct AnswerverifiedShow Answer

The capability index (Cpk) indicates the position of the mean and tails of a process's variance relative to design specifications.

Correct AnswerverifiedShow Answer

The producer's risk associated with rejecting a high-quality lot is denoted in acceptance sampling with the Greek letter beta.

Correct AnswerverifiedShow Answer

In monitoring process quality, we might use which of the following statistics?

Correct AnswerverifiedShow Answer

The p-chart is only useful for sampling that deals with continuous variables.

Correct AnswerverifiedShow Answer

Quality control charts usually have a central line and upper and lower control limit lines. Which of the following is not a reason that the process being monitored with the chart should be investigated?

Correct AnswerverifiedShow Answer

If there are 40 total defects from 8 samples, each sample consisting of 200 individual items in a production process, which of the following is the fraction defective that can be used in a p-chart for quality control purposes?

Correct AnswerverifiedShow Answer

It is impossible to have zero variability in production processes.

Correct AnswerverifiedShow Answer

Attributes are those quality characteristics that are classified as either conforming or not conforming to specification.

Correct AnswerverifiedShow Answer

An example of assignable variation in a production system may be that workers are not identically trained.

Correct AnswerverifiedShow Answer

You have just used the capability index (Cpk) formulas to compute the two values "min [1.5, 1]." Which of the following is the proper interpretation of these numbers?

Correct AnswerverifiedShow Answer

If the fraction defective is 0.4 based on a sample size of 100, the standard deviation used in the p-chart is about 0.10.

Correct AnswerverifiedShow Answer

For which of the following should we use an R-chart to monitor process quality?

Correct AnswerverifiedShow Answer

One hundred percent inspection is justified when the cost of inspection is low.

Correct AnswerverifiedShow Answer

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You are going to develop an R-chart based on range statistics, and you are using a sample size of 9 for your charting purposes. Which of the following is the lower control limit D₃ factor for the chart?

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