Question 1

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

Accepted Answer

A) True 
 B)False

Question 2

Acceptance sampling is performed on goods that already exist to determine what percentage of items conforms to specifications.

Accepted Answer

A) True 
 B)False

Question 3

Total, 100 percent inspection can never be cost justified.

Accepted Answer

A) True 
 B)False

Question 4

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

Accepted Answer

A) True 
 B)False

Question 5

If there are 120 total defects from 10 samples, each sample consisting of 10 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) 120 
B) 10 
C) 8 
D) 1.2 
E) 0.8 
A) 120 
B) 10 
C) 8 
D) 1.2 
E) 0.8

Question 6

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

Accepted Answer

A) True 
 B)False

Question 7

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 8

The Greek letter alpha is associated with consumer's risk.

Accepted Answer

A) True 
 B)False

Question 9

In acceptance sampling, the number of units in the sample (n) is determined by the interaction of the acceptable quality level (AQL), the lot tolerance percent defective (LTPD), the probability of rejecting a high-quality lot (alpha), and the probability of accepting a low-quality lot (beta).

Accepted Answer

A) True 
 B)False

Question 10

You have just used the capability index (Cpk) formulas to compute the two values "min [2, 2.5]." Which of the following is the proper interpretation of these numbers?

Accepted Answer

A) The true capability index value is 2.5. 
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 2 and 2.5. 
A) The true capability index value is 2.5. 
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 2 and 2.5.

Question 11

You want to determine the lower control line for a p-chart for quality control purposes.You take several samples of a size of 50 items in your production process.From the samples, you determine the fraction defective is 0.006 and the standard deviation is 0.001.If the desired confidence level is 99.7 percent, which of the following is the resulting LCL value for the line?

Accepted Answer

A) 0.0 
B) 0.002 
C) 0.003 
D) 0.004 
E) None of these 
A) 0.0 
B) 0.002 
C) 0.003 
D) 0.004 
E) None of these

Question 12

Comparing traditional view of the cost of variability and Taguchi's view of cost of variability,

Accepted Answer

A) Both views are about the same. 
B) Traditional view holds that as long as the product is within specification, there is no difference. 
C) Taguchi's view holds that closer to the midpoint of specifications better it is. 
D) B and C are true. 
E) None of the above. 
A) Both views are about the same. 
B) Traditional view holds that as long as the product is within specification, there is no difference. 
C) Taguchi's view holds that closer to the midpoint of specifications better it is. 
D) B and C are true. 
E) None of the above.

Question 13

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 99.7 percent, and the average of the sample means is 24.Which of the following is your UCL?

Accepted Answer

A) 36 
B) 24 
C) 12 
D) 4 
E) None of these 
A) 36 
B) 24 
C) 12 
D) 4 
E) None of these

Question 14

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

Question 15

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 
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 16

Standard practice in statistical process control for variables is to set control limits so that 95 percent of the sample means will fall within the UCL and the LCL.

Accepted Answer

A) True 
 B)False

Question 17

LTPD in acceptance sampling stands for lot tolerance for parts defective.

Accepted Answer

A) True 
 B)False

Question 18

You are going to develop an X-bar chart based on range statistics, and you are using a sample size of 12 for your charting purposes.Which of the following is the A2 factor for the X-bar chart?

Accepted Answer

A) 0.37 
B) 0.31 
C) 0.27 
D) 0.22 
E) 0.18 
A) 0.37 
B) 0.31 
C) 0.27 
D) 0.22 
E) 0.18

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" 
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

You are going to develop an R-chart based on range statistics, and you are using a sample size of 15 for your charting purposes.Which of the following is the upper control limit D4 factor for the chart?

Accepted Answer

A) 1.65 
B) 1.70 
C) 1.76 
D) 1.87 
E) 1.92 
A) 1.65 
B) 1.70 
C) 1.76 
D) 1.87 
E) 1.92

Exam 13: Statistical Quality Control

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

Acceptance sampling is performed on goods that already exist to determine what percentage of items conforms to specifications.

Total, 100 percent inspection can never be cost justified.

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

If there are 120 total defects from 10 samples, each sample consisting of 10 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?

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

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

The Greek letter alpha is associated with consumer's risk.

In acceptance sampling, the number of units in the sample (n) is determined by the interaction of the acceptable quality level (AQL), the lot tolerance percent defective (LTPD), the probability of rejecting a high-quality lot (alpha), and the probability of accepting a low-quality lot (beta).

You have just used the capability index (Cpk) formulas to compute the two values "min [2, 2.5]." Which of the following is the proper interpretation of these numbers?

Comparing traditional view of the cost of variability and Taguchi's view of cost of variability,

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 99.7 percent, and the average of the sample means is 24.Which of the following is your UCL?

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?

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

Standard practice in statistical process control for variables is to set control limits so that 95 percent of the sample means will fall within the UCL and the LCL.

LTPD in acceptance sampling stands for lot tolerance for parts defective.

You are going to develop an X-bar chart based on range statistics, and you are using a sample size of 12 for your charting purposes.Which of the following is the A2 factor for the X-bar chart?

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

You are going to develop an R-chart based on range statistics, and you are using a sample size of 15 for your charting purposes.Which of the following is the upper control limit D4 factor for the chart?

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You are going to develop an X-bar chart based on range statistics, and you are using a sample size of 12 for your charting purposes.Which of the following is the A₂ factor for the X-bar chart?