Deck 16: Quality Control and Spc

Question 1

(Students must compute the range per sample and overall r-bar)
$\text { Table 1-SPC Problem Data }$
$\text { Observation Number }$
$\begin{array}{|c|r|r|r|r|c|}\hline \text { Sample number } &1&2&3& 4 & 5 \\\hline 1 & 10.1 & 10.6 & 9.8 & 9.9 & 10.9 \\2 & 9.7 & 9.5 & 10.3 & 9.9 & 10.5 \\3 & 10.1 & 10.7 & 9.2 & 10.0 & 10.1 \\4 & 9.9 & 9.8 & 10.5 & 10.4 & 10.1 \\5 & 10.4 & 10.1 & 10.9 & 9.9 & 10.3 \\\hline\end{array}$

-Using Table 1, for the R-chart, what is the value of LCL_R?

A) Less than or equal to 0.01
B) Greater than 0.01 but less than or equal to 0.02
C) Greater than 0.02 but less than or equal to 0.03
D) Greater than 0.03

Answer 1

Less than or equal to 0.01

Question 2

A plastic cell phone case has been experiencing physical quality control problems. That is, the clear screen does not always fit (and snap into place) on the case. The dimensions of the screen have consistently been in statistical process control (SPC). A root cause quality initiative collected the following data about the plastic cell phone case. Analyze the width of the cell phone case using control charts and make a recommendation.
Table 1 Cell Phone Plastic Case Widths in Centimeters Data*
$\begin{array} { | c | c | c | c | c | c | c | c | } \hline & \text { Sample 1 } & \text { Sample 2 } & \text { Sample 3 } & \text { Sample 4 } & \text { Sample 5 } & \text { Sample 6 } & \text { Sample 7 } \\\hline \text { Observation } & & & & & & & \\\hline \# 1 & 6.02 & 5.92 & 5.88 & 5.99 & 6.05 & 5.94 & 6.00 \\\hline \# 2 & 5.97 & 5.83 & 5.97 & 6.08 & 6.06 & 5.96 & 5.95 \\\hline \# 3 & 5.90 & 5.87 & 5.88 & 6.08 & 5.98 & 5.99 & 5.82 \\\hline \text { Average } & 5.963 & 5.873 & 5.91 & 6.05 & 6.03 & 5.963 & 5.923 \\\hline \text { Range } & 0.12 & 0.09 & 0.09 & 0.09 & 0.08 & 0.05 & 0.18 \\\hline\end{array}$ *The sample averages and ranges helps in avoiding simple math errors and quickens the time to complete the SPC analysis.

-Given the previous results and analysis for the R-chart, one would:

A) conclude that the R-chart is in statistical process control, and proceed to develop the x-bar chart.
B) conclude that the R-chart is not in statistical process control, and search for common causes of the problem (i.e., the root cause).
C) conclude that the R-chart is not in statistical process control, and proceed to develop the x-bar chart.
D) plot the sample means first to see if they are randomly distributed.

Answer 2

conclude that the R-chart is not in statistical process control, and search for common causes of the problem (i.e., the root cause).

Question 3

Table 1 Statistical Process Control (SPC) Problem Data*
$\begin{array}{|c|c|c|c|c|c|}\hline \text { Sample } & \begin{array}{c}\text { Observation } \\\text { Number }\end{array} & \begin{array}{c}\text { Observation } \\\text { Number }\end{array} & \begin{array}{c}\text { Observation } \\\text { Number }\end{array} \\\hline \text { Number } & 1 & 2 & 3 & \begin{array}{c}\text { Row } \\\text { Average }\end{array} & \text { Row Range } \\\hline 1 & 10.1 & 10.6 & 9.6 & 10.1 & 1.00 \\\hline 2 & 9.7 & 9.4 & 9.0 & 9.37 & 0.70 \\\hline 3 & 10.1 & 9.1 & 10.3 & 9.83 & 1.20 \\\hline 4 & 10.1 & 10.3 & 10.9 & 10.43 & 0.80 \\\hline 5 & 10.2 & 9.8 & 9.0 & 9.67 & 1.20 \\\hline 6 & 10.6 & 10.2 & 9.5 & 10.10 & 1.10 \\\hline 7 & 9.5 & 10.2 & 10.2 & 9.97 & 0.70 \\\hline\end{array}$ *The range and row average help you avoid simple math errors and quicken the time to complete the SPC analysis but you have to know what to use when.

-Given the previous results and analysis for the R-chart, one would:

A) conclude that the R-chart is in statistical control and proceed to develop the x-bar chart.
B) conclude that the R-chart is not in statistical control and proceed to develop the x-bar chart.
C) investigate sample # 3 as it is outside the R-chart control limits and redo the R-chart.
D) plot the x-bar sample means first to see if they are randomly distributed.

Answer 3

conclude that the R-chart is in statistical control and proceed to develop the x-bar chart.

Question 4

(Students must compute the range per sample and overall r-bar)
$\text { Table 1-SPC Problem Data }$
$\text { Observation Number }$
$\begin{array}{|c|r|r|r|r|c|}\hline \text { Sample number } &1&2&3& 4 & 5 \\\hline 1 & 10.1 & 10.6 & 9.8 & 9.9 & 10.9 \\2 & 9.7 & 9.5 & 10.3 & 9.9 & 10.5 \\3 & 10.1 & 10.7 & 9.2 & 10.0 & 10.1 \\4 & 9.9 & 9.8 & 10.5 & 10.4 & 10.1 \\5 & 10.4 & 10.1 & 10.9 & 9.9 & 10.3 \\\hline\end{array}$

-In Table 1, the sample values represent service times in minutes. For the R-chart, what is the value of UCL_R?

A) Less than or equal to 0.94
B) Greater than 0.94 but less than or equal to 0.99
C) Greater than 0.99 but less than or equal to 1.99
D) Greater than 1.99

Question 5

(Students must compute the range per sample and overall r-bar)
$\text { Table 1-SPC Problem Data }$
$\text { Observation Number }$
$\begin{array}{|c|r|r|r|r|c|}\hline \text { Sample number } &1&2&3& 4 & 5 \\\hline 1 & 10.1 & 10.6 & 9.8 & 9.9 & 10.9 \\2 & 9.7 & 9.5 & 10.3 & 9.9 & 10.5 \\3 & 10.1 & 10.7 & 9.2 & 10.0 & 10.1 \\4 & 9.9 & 9.8 & 10.5 & 10.4 & 10.1 \\5 & 10.4 & 10.1 & 10.9 & 9.9 & 10.3 \\\hline\end{array}$

-Given the previous results and analysis for the R-chart, one would:

A) conclude that the R-chart is in statistical control, and proceed to develop the x-bar chart.
B) conclude that the R-chart is not in statistical control, and proceed to develop the x-bar chart.
C) investigate sample # 3 as it is outside the R-chart control limits and redo the R-chart.
D) conclude that the variation is not random, and therefore all samples should be investigated.

Question 6

Quality at the source means that quality is controlled by _____.

A) people responsible for the work
B) quality control managers
C) front line supervisors
D) top management

Question 7

A plastic cell phone case has been experiencing physical quality control problems. That is, the clear screen does not always fit (and snap into place) on the case. The dimensions of the screen have consistently been in statistical process control (SPC). A root cause quality initiative collected the following data about the plastic cell phone case. Analyze the width of the cell phone case using control charts and make a recommendation.
Table 1 Cell Phone Plastic Case Widths in Centimeters Data*
$\begin{array} { | c | c | c | c | c | c | c | c | } \hline & \text { Sample 1 } & \text { Sample 2 } & \text { Sample 3 } & \text { Sample 4 } & \text { Sample 5 } & \text { Sample 6 } & \text { Sample 7 } \\\hline \text { Observation } & & & & & & & \\\hline \# 1 & 6.02 & 5.92 & 5.88 & 5.99 & 6.05 & 5.94 & 6.00 \\\hline \# 2 & 5.97 & 5.83 & 5.97 & 6.08 & 6.06 & 5.96 & 5.95 \\\hline \# 3 & 5.90 & 5.87 & 5.88 & 6.08 & 5.98 & 5.99 & 5.82 \\\hline \text { Average } & 5.963 & 5.873 & 5.91 & 6.05 & 6.03 & 5.963 & 5.923 \\\hline \text { Range } & 0.12 & 0.09 & 0.09 & 0.09 & 0.08 & 0.05 & 0.18 \\\hline\end{array}$ *The sample averages and ranges helps in avoiding simple math errors and quickens the time to complete the SPC analysis.

-Using Table 1 for the R-chart, what is the value of UCL_R?

A) Less than or equal to 0.2
B) Greater than 0.2 but less than or equal to 0.3
C) Greater than 0.3 but less than or equal to 0.4
D) Greater than 0.4

Question 8

Common cause variation _____.

A) is controllable by employees (labor) only
B) is also called assignable cause variation
C) can be easily detected by statistical process control methods
D) can be reduced if training is provided by management

Question 9

Table 1 Statistical Process Control (SPC) Problem Data*
$\begin{array}{|c|c|c|c|c|c|}\hline \text { Sample } & \begin{array}{c}\text { Observation } \\\text { Number }\end{array} & \begin{array}{c}\text { Observation } \\\text { Number }\end{array} & \begin{array}{c}\text { Observation } \\\text { Number }\end{array} \\\hline \text { Number } & 1 & 2 & 3 & \begin{array}{c}\text { Row } \\\text { Average }\end{array} & \text { Row Range } \\\hline 1 & 10.1 & 10.6 & 9.6 & 10.1 & 1.00 \\\hline 2 & 9.7 & 9.4 & 9.0 & 9.37 & 0.70 \\\hline 3 & 10.1 & 9.1 & 10.3 & 9.83 & 1.20 \\\hline 4 & 10.1 & 10.3 & 10.9 & 10.43 & 0.80 \\\hline 5 & 10.2 & 9.8 & 9.0 & 9.67 & 1.20 \\\hline 6 & 10.6 & 10.2 & 9.5 & 10.10 & 1.10 \\\hline 7 & 9.5 & 10.2 & 10.2 & 9.97 & 0.70 \\\hline\end{array}$ *The range and row average help you avoid simple math errors and quicken the time to complete the SPC analysis but you have to know what to use when.

-Using Table 1, the sample values represent service times in minutes. For the R-chart, what is the value of UCL_R?

A) Less than or equal to 1.0
B) Greater than 1.0 but less than or equal to 1.5
C) Greater than 1.5 but less than or equal to 2.0
D) Greater than 2.0 but less than or equal to 2.5

Question 10

Which of the following statements is NOT TRUE about special cause variations?

A) They disrupt the random patterns of common cause variations.
B) They arise from internal sources only.
C) They appear sporadically.
D) They are easily detectable using statistical methods.

Question 11

Testing whether a computer boots up the first time is an example of _____.

A) supplier certification and management
B) in-process control
C) finished-goods control
D) a continuous metric

Question 12

If no special causes affect the output of a process, the process is said to be _____; and if special causes are present, the process is said to be _____.

A) qualified; not qualified
B) in control; out of control
C) capable; not capable
D) certified; not certified

Question 13

A plastic cell phone case has been experiencing physical quality control problems. That is, the clear screen does not always fit (and snap into place) on the case. The dimensions of the screen have consistently been in statistical process control (SPC). A root cause quality initiative collected the following data about the plastic cell phone case. Analyze the width of the cell phone case using control charts and make a recommendation.
Table 1 Cell Phone Plastic Case Widths in Centimeters Data*
$\begin{array} { | c | c | c | c | c | c | c | c | } \hline & \text { Sample 1 } & \text { Sample 2 } & \text { Sample 3 } & \text { Sample 4 } & \text { Sample 5 } & \text { Sample 6 } & \text { Sample 7 } \\\hline \text { Observation } & & & & & & & \\\hline \# 1 & 6.02 & 5.92 & 5.88 & 5.99 & 6.05 & 5.94 & 6.00 \\\hline \# 2 & 5.97 & 5.83 & 5.97 & 6.08 & 6.06 & 5.96 & 5.95 \\\hline \# 3 & 5.90 & 5.87 & 5.88 & 6.08 & 5.98 & 5.99 & 5.82 \\\hline \text { Average } & 5.963 & 5.873 & 5.91 & 6.05 & 6.03 & 5.963 & 5.923 \\\hline \text { Range } & 0.12 & 0.09 & 0.09 & 0.09 & 0.08 & 0.05 & 0.18 \\\hline\end{array}$ *The sample averages and ranges helps in avoiding simple math errors and quickens the time to complete the SPC analysis.

-Using Table 1, for the X-chart, what is the value of UCL_X?

A) Less than or equal to 3.0
B) Greater than 3.0 but less than or equal to 4.0
C) Greater than 4.0 but less than or equal to 5.0
D) Greater than 5.0

Question 14

A Proctor and Gamble factory process fills boxes with detergent. Construct an appropriate set of control charts to monitor the process. Historical data for fill weight (in ounces) of eight samples is presented below. A sample size of six was used.
$\begin{array} { c c c } \text { Sample } & \text { Sample Mean } & \text { Sample Range } \\\hline 1 & 15.80 & 0.42 \\2 & 16.10 & 0.38 \\3 & 16.02 & 0.08 \\4 & 15.95 & 0.15 \\5 & 16.12 & 0.42 \\6 & 16.18 & 0.23 \\7 & 15.87 & 0.36 \\8 & 16.20 & 0.40\end{array}$ Worksheet (this will not be graded but will help you answer exam questions)


-For the Proctor and Gamble detergent box problem, the upper control limit for the range chart is _____.

A) less than or equal to 0.6
B) more than 0.6 but less than or equal to 0.7
C) more than 0.7 but less than or equal to 0.8
D) more than 0.8

Question 15

Common cause variation:

A) is a natural part of the technology and process design and cannot be controlled.
B) is easily detectable with statistical methods and control charts.
C) cannot be reduced even if better technology, process design, or training is provided.
D) can be reduced through corrective action, which is the responsibility of the workers who run the processes.

Question 16

Table 1 Statistical Process Control (SPC) Problem Data*
$\begin{array}{|c|c|c|c|c|c|}\hline \text { Sample } & \begin{array}{c}\text { Observation } \\\text { Number }\end{array} & \begin{array}{c}\text { Observation } \\\text { Number }\end{array} & \begin{array}{c}\text { Observation } \\\text { Number }\end{array} \\\hline \text { Number } & 1 & 2 & 3 & \begin{array}{c}\text { Row } \\\text { Average }\end{array} & \text { Row Range } \\\hline 1 & 10.1 & 10.6 & 9.6 & 10.1 & 1.00 \\\hline 2 & 9.7 & 9.4 & 9.0 & 9.37 & 0.70 \\\hline 3 & 10.1 & 9.1 & 10.3 & 9.83 & 1.20 \\\hline 4 & 10.1 & 10.3 & 10.9 & 10.43 & 0.80 \\\hline 5 & 10.2 & 9.8 & 9.0 & 9.67 & 1.20 \\\hline 6 & 10.6 & 10.2 & 9.5 & 10.10 & 1.10 \\\hline 7 & 9.5 & 10.2 & 10.2 & 9.97 & 0.70 \\\hline\end{array}$ *The range and row average help you avoid simple math errors and quicken the time to complete the SPC analysis but you have to know what to use when.

-Using Table 1, for the R-chart, what is the value of LCL_R?

A) Less than or equal to 1.0
B) Greater than 1.0 but less than or equal to 1.5
C) Greater than 1.5 but less than or equal to 2.0
D) Greater than 2.0

Question 17

In the 1:10:100 Rule, which of the following would be correct?

A) If a defect or service error is identified and corrected at the design stage, it might cost $100 to fix.
B) If a defect or service error is identified and corrected at the production process stage, it might cost $100 to fix.
C) If a defect or service error is identified and corrected after it reaches the customer, it might cost $100 to fix.
D) If a defect or service error is identified and corrected at the design stage, it might cost $1 x $10 x $100 = $1,000 to fix.

Question 18

Which of the following statements is TRUE about common cause variations?

A) They can be controlled and described in a non-statistical method.
B) They appear at random, and individual sources cannot be identified or explained.
C) They account for about 10 to 15 percent of the observed variation in a process.
D) They arise from external sources that are not inherent in the process.

Question 19

Evaluating the trade-offs between the costs of detection or replacement of a defective part and costs of allowing a nonconformity to continue through the production process is related to _____.

A) supplier certification and management
B) in-process control
C) finished-goods control
D) a continuous metric

Question 20

Common causes of variation:

A) occur when 2 of 3 consecutive points on a statistical process control chart are above or below the center line of the chart.
B) occur when adjusting a process that is already in control.
C) generally account for 80 to 95 percent of the observed variation in a process.
D) can be prevented, explained, and easily understood.

Question 21

Which of the following is most closely related to a discrete metric?

A) R-charts
B) x-bar charts
C) c-charts
D) Process capability indices

Question 22

If one was monitoring the average time to load a web page, the chart to use would be a(n) _____.

A) R- or x-bar chart
B) sample-size chart
C) p-chart
D) c-chart

Question 23

Table 1-Statistical Process Control (SPC) Problem Data for Service Waiting Times
$\begin{array} { | c | c | c | c | } \hline \begin{array} { c } \text { Sample } \\\text { Number }\end{array} & \multicolumn{3}{|c|} { \text { Observation Number } } \\\hline & 1 & 2 & 3 \\\hline 1 & 9.6 & 10.2 & 9.8 \\\hline 2 & 9.4 & 10.0 & 10.4 \\\hline 3 & 9.9 & 9.6 & 9.0 \\\hline 4 & 9.3 & 10.5 & 9.9 \\\hline 5 & 9.7 & 9.2 & 9.7 \\\hline\end{array}$

-Given the previous results and analysis for the R-chart regarding service waiting times, one would:

A) conclude that the R-chart is in statistical control and proceed to develop the x-bar chart.
B) conclude that the R-chart is not in statistical control and proceed to develop the x-bar chart.
C) investigate sample # 3 as it is outside the R-chart control limits and redo the R-chart.
D) conclude that the variation is not random and the decreasing trend in the range should be investigated.

Question 24

The center line (p-bar) for a p-chart is 0.50 with an ULC = 0.70 and a LCL = 0.35. The results of the next eight sample means are 0.45, 0.60, 0.39, 0.44, 0.48, 0.58, 0.54, and 0.64. Which of the following actions should be taken in this scenario?

A) Nothing-the process is in control.
B) Investigate assignable causes because four observations are above the center line.
C) Investigate assignable causes because there is a bad trend (run).
D) Investigate assignable causes because four of the eight samples are below the center line.

Question 25

Identify the chart that is also known as fraction nonconforming or fraction defective chart.

A) A p-chart
B) A c-chart
C) An x-chart
D) An r-chart

Question 26

Table 1-Statistical Process Control (SPC) Problem Data for Service Waiting Times
$\begin{array} { | c | c | c | c | } \hline \begin{array} { c } \text { Sample } \\\text { Number }\end{array} & \multicolumn{3}{|c|} { \text { Observation Number } } \\\hline & 1 & 2 & 3 \\\hline 1 & 9.6 & 10.2 & 9.8 \\\hline 2 & 9.4 & 10.0 & 10.4 \\\hline 3 & 9.9 & 9.6 & 9.0 \\\hline 4 & 9.3 & 10.5 & 9.9 \\\hline 5 & 9.7 & 9.2 & 9.7 \\\hline\end{array}$

-In Table 1, the sample values represent service waiting times in minutes. For the R-chart, what is the value of UCL_R?

A) Less than or equal to 1.5
B) Greater than 1.5 but less than or equal to 2.0
C) Greater than 2.0 but less than or equal to 2.5
D) Greater than 2.5

Question 27

A Proctor and Gamble factory process fills boxes with detergent. Construct an appropriate set of control charts to monitor the process. Historical data for fill weight (in ounces) of eight samples is presented below. A sample size of six was used.
$\begin{array} { c c c } \text { Sample } & \text { Sample Mean } & \text { Sample Range } \\\hline 1 & 15.80 & 0.42 \\2 & 16.10 & 0.38 \\3 & 16.02 & 0.08 \\4 & 15.95 & 0.15 \\5 & 16.12 & 0.42 \\6 & 16.18 & 0.23 \\7 & 15.87 & 0.36 \\8 & 16.20 & 0.40\end{array}$ Worksheet (this will not be graded but will help you answer exam questions)


-For the Proctor and Gamble detergent box problem, based on the control charts it can be said that _____.

A) both the R- and X-bar charts are not in statistical control
B) the R-chart is not in statistical control, but the X-bar chart is in statistical control
C) the R-chart is not in statistical control, but the X-bar chart is in statistical control, and therefore, the process should be stopped and sources of error investigated
D) the R-chart is in statistical control, but the X-bar chart is not in statistical control, and therefore, the process should be stopped and sources of error investigated

Question 28

The center line (p-bar) for a p-chart is 0.50 with an ULC = 0.65 and a LCL = 0.35. The results of the next eight sample means are 0.45, 0.60, 0.39, 0.44, 0.48, 0.58, 0.54, and 0.64. Which of the following is the best action to take?

A) Collect eight additional samples and then decide.
B) Wait and collect more data by increasing the sample size.
C) Investigate assignable causes because four observations are above the center line.
D) Investigate assignable causes because there is a bad trend (run).

Question 29

A c-chart _____.

A) is used for the fraction of nonconforming items
B) is used to monitor the number of nonconformances per unit
C) uses continuous metrics
D) can have negative lower limits

Question 30

Which is NOT related to a discrete metric?

A) Counting
B) Visual yes or no inspection
C) Good or bad
D) Time

Question 31

Indications in a control chart of an out-of-control situation include all of the following EXCEPT:

A) a shift in the average value.
B) the same number of points above and below the center line.
C) points that lie outside upper and lower control limits.
D) a cyclical pattern in the chart.

Question 32

Which of the following statements is TRUE?

A) Common cause variation arises from external sources that are not inherent in the process and is where statistical quality control methods are most useful.
B) If the metric is discrete, a p- or c-chart is normally used.
C) Statistical process control is not used in hospitals due to the high liability costs.
D) Statistical process control charts are most efficient when trying to monitor and control 5- and 6-sigma quality levels.

Question 33

Given that 20 samples are taken in a control chart initiative, the probability that 5 consecutive samples are below the center line in an R- or x-bar chart is _____.

A) 0.02500
B) 0.03125
C) 0.06250
D) 0.25000

Question 34

A Proctor and Gamble factory process fills boxes with detergent. Construct an appropriate set of control charts to monitor the process. Historical data for fill weight (in ounces) of eight samples is presented below. A sample size of six was used.
$\begin{array} { c c c } \text { Sample } & \text { Sample Mean } & \text { Sample Range } \\\hline 1 & 15.80 & 0.42 \\2 & 16.10 & 0.38 \\3 & 16.02 & 0.08 \\4 & 15.95 & 0.15 \\5 & 16.12 & 0.42 \\6 & 16.18 & 0.23 \\7 & 15.87 & 0.36 \\8 & 16.20 & 0.40\end{array}$ Worksheet (this will not be graded but will help you answer exam questions)


-For the Proctor and Gamble detergent box problem, the lower control limit for the x-bar chart is _____.

A) less than or equal to 12
B) more than 12 but less than or equal to 14
C) more than 14 but less than or equal to 16
D) more than 16

Question 35

Which of the following is NOT related to a continuous metric?

A) Length
B) x-bar and R-charts
C) p-chart
D) Time

Question 36

Table 1-Statistical Process Control (SPC) Problem Data for Service Waiting Times
$\begin{array} { | c | c | c | c | } \hline \begin{array} { c } \text { Sample } \\\text { Number }\end{array} & \multicolumn{3}{|c|} { \text { Observation Number } } \\\hline & 1 & 2 & 3 \\\hline 1 & 9.6 & 10.2 & 9.8 \\\hline 2 & 9.4 & 10.0 & 10.4 \\\hline 3 & 9.9 & 9.6 & 9.0 \\\hline 4 & 9.3 & 10.5 & 9.9 \\\hline 5 & 9.7 & 9.2 & 9.7 \\\hline\end{array}$

-Using Table 1, for the R-chart, what is the value of LCL_R?

A) Less than or equal to 1.0
B) Greater than 1.0 but less than or equal to 1.5
C) Greater than 1.5 but less than or equal to 2.0
D) Greater than 2.0

Question 37

Honda wants to monitor the number of blemishes (scratches, blisters, etc.) on the fenders of its cars using a statistical process control chart. The most appropriate type of statistical process control (SPC) chart that can be used in this scenario is a(n) _____.

A) x-bar chart
B) R-chart
C) Cpk chart
D) c-chart

Question 38

To monitor the fraction of printed circuit boards that do not pass a functional test, a(n) _____ is used.

A) k-chart
B) p-chart
C) c-chart
D) R-chart

Question 39

A p-chart _____.

A) is used to monitor the proportion of nonconforming items
B) counts the number of nonconformances per unit
C) uses continuous metrics
D) can have negative lower limits

Question 40

Which of the following suggests a process that is NOT in control?

A) Points follow a smooth pattern from the lower control limit to the upper control limit.
B) The number of points above and below the center line is about the same.
C) Points fall randomly above and below the center line.
D) No points are outside the control limits.

Question 41

In manufacturing, quality control is generally applied at the receiving stage from suppliers, during various production processes, and at the finished-goods stage.

Question 42

Common causes of variation generally accounts for about 80 to 90 percent of the observed variation within a process.

Question 43

The 1:10:100 Rule supports the need for control and a focus on prevention by building quality at the source.

Question 44

Flaws are counted on a standard steel plate (sheet). Each sheet has the exact same dimensions. If 10 sheets are selected at random and the number of flaws per sheet is as follows, determine the lower and upper control limits. $\begin{array} { | c | c | } \hline \text { Sheet } & \text { Number of Flaws } \\\hline 1 & 3 \\\hline 2 & 1 \\\hline 3 & 3 \\\hline 4 & 0 \\\hline 5 & 2 \\\hline 6 & 2 \\\hline 7 & 0 \\\hline 8 & 1 \\\hline 9 & 1 \\\hline 10 & 2 \\\hline\end{array}$ The upper control limit (UCL) for the steel plate control chart is _____.

A) less than 3
B) more than or equal to 3 but less than 4
C) more than or equal to 4 but less than 5
D) more than or equal to 5 but less than 6

Question 45

With good management, all variability of output from any goods- or service-producing process can be eliminated.

Question 46

In-process quality control is typically performed by the employees who run the processes.

Question 47

Historically, the average proportion of defective bars has been 0.015. Samples will be of 100 bars each. Construct a p-chart using $$z = 3$$ . Suppose a sample had 0.054 defectives. What would be the best action to take in this scenario?

A) Nothing; it appears to be random variation.
B) Look for assignable causes.
C) Change z to 2 and take another sample.
D) Change z to 4 and continue sampling.

Question 48

Quality at the source focuses on supplier quality at the beginning of a value chain.

Question 49

A supplier is producing a machined part for the transmission of a vehicle. The upper specification limit is 0.125 cm, and the lower specification limit is 0.085. The process standard deviation for the process that makes this part is 0.008, and the process average is 0.105. What conclusion can be drawn from these process capability data?

A) The process is centered and capable.
B) The process is not centered and capable.
C) The process is centered and not capable.
D) The process is not centered and not capable.

Question 50

The goal of statistical process control (SPC) is to help identify and eliminate unwanted causes of variation.

Question 51

A key element of a control system is the ability to measure performance and compare it to a performance standard.

Question 52

It generally costs more to correct an error or defect at the design stage than after it has reached the customer.

Question 53

A supplier is producing a machined part for the transmission of a vehicle. The upper specification limit is 0.135 cm, and the lower specification limit is 0.075. The process standard deviation for the process that makes this part is 0.005, and the process average is 0.105. What conclusion can be drawn from these process capability data?

A)The process is centered and capable.
B)The process is not centered and capable.
C)The process is centered and not capable.
D)The process is not centered and not capable.

Question 54

The time to check out guests at a hotel front desk was measured over the course of several weeks. Management believes that the target time for checking out guests should be between 2 and 3 minutes with a target of 2.5 minutes. The data gathered for the actual process had a mean time of 2.75 minutes with a standard deviation of 0.45 minutes. Find and interpret Cp, Cpl, Cpu, and Cpk in the context of this situation. Which one of the following statements is TRUE?

A) The process is centered and not capable.
B) The process is centered and capable.
C) The process is not centered and capable.
D) The process is not centered and not capable.

Question 55

Historically, the average proportion of defective bars has been 0.015. Samples will be of 100 bars each. Construct a p-chart using $$z = 3$$ . Suppose a sample had 0.044 defectives. What would be the best action to take in this scenario?

A) Nothing; it appears to be random variation.
B) Look for assignable causes.
C) Change z to 2 and take another sample.
D) Change z to 4 and continue sampling.

Question 56

A bottling process sometimes results in overfills or underfills. Overfills are especially damaging to the equipment. Which process capability index would this company most want to monitor?

A) C_p
B) C_pl
C) C_pu
D) C_pk

Question 57

Quality control ensures that a good or service conforms to specifications and meets customer requirements.

Question 58

The lower and upper specification limits for a component are 4.20 and 4.30 ounces, respectively. The process standard deviation is .02, and the process average is 4.24 ounces. Which one of the following statements is TRUE?

A) The C_p index indicates the process is centered.
B) The C_p index indicates the process is not centered.
C) The C_pk index indicates the process is centered.
D) The C_pk index indicates the process is not centered.

Question 59

Common causes of variations generally accounts for about 10 to 15 percent of the observed variation within a process.

Question 60

Quality control of front-office operations in services uses the same techniques that are applied in manufacturing.

Question 61

If process quality approaches six sigma levels, then standard types of control charts are not useful.

Question 62

To account for the process centering, two-sided capability index is often used.

Question 63

When the range of process variation does not conform to the design specifications, the process capability index will be less than 1.

Question 64

Over-adjusting a process that is in control will usually increase the variation in the output.

Question 65

The value of C_pk is the average of the lower and upper capability indexes; that is, C_pk = (C_pl + C_pu)/2.

Question 66

In developing process control charts, if special causes are present, then they are not representative of the true state of statistical control, and the calculations of the center line and control limits will be biased.

Question 67

Which one of the following statements about the Casey Company case study on quality management is TRUE?

A) The first step in this case analysis was to create a process flowchart and checksheet.
B) Control charts verify that all aspects of the process are in statistical process control.
C) Control charts verify that the data entry employee was doing an excellent job.
D) The R-chart for this statistical process control analysis was out of control.

Question 68

Both the p-chart and c-chart use continuous data.

Question 69

Process capability quantifies the variation that results from common causes.

Question 70

A process is considered to be in control when all common and special cause variations have been eliminated.

Question 71

As long as there are no points outside of the control limits in a control chart, the process would always be considered to be in control.

Question 72

An R-chart is always analyzed first because the control limits in the R-chart depend on the mean of the data.

Question 73

Special cause variation tends to be easily detectable using statistical methods.

Question 74

Poor quality that might result from a broken tool or an employee who is ill would be an example of special cause variation.

Question 75

Larger sample sizes allow smaller changes in process characteristics to be detected with higher probability.

Question 76

The lower the rate of defects, the higher the sample size should be in p-charts.

Question 77

It is not necessary to have a process in control when establishing control limits.

Question 78

A system governed only by common causes is called a stable system.

Question 79

A c-chart is used to monitor the proportion of nonconforming units, whereas a p-chart is used to monitor the number of nonconformances per unit.

Question 80

Collecting continuous data is usually easier than collecting discrete data.