Question 1

Why are there eight tests for control for$\bar { X }$ charts but only
four for R charts?

Accepted Answer

(Because given sufficient sample size, $\bar { X }$ may be assumed to be
normally distributed, which allows for additional tests.No such
assumption may be made for the distribution of R.)

Question 2

Suppose a manufacturer of canned corn randomly selects five cans of corn each hour and counts the number of kernels in these cans in order to assess quality.For the first thirty hours the average number of kernels in the 150 cans tested was 245.26.The average range for the thirty samples was 12.45.On the basis of this data:A.Determine the upper and lower control limits for the X-bar chart.
B.Determine the upper and lower control limits for the R chart.

Accepted Answer

a.(UCL = 245.26 + (3 * 12.45/(2.326 * SQRT(5))) = 245.26 + 7.18 = 252.44
LCL = 245.26 - 7.18 = 238.08)

b.(UCL = 2.114 * 12.45 = 26.32.LCL = 0 * 12.45 = 0.)

Question 3

Sources of random error in monitoring a production process for quality control purposes include:

Accepted Answer

A)  miscalibration of measuring devices.
B)  transposition of numbers in recording measurements.
C)  not sampling from each of multiple production lines.
D)  sampling at exactly the same time each hour. B

Question 4

A full day's quality control tests (24 points) all fall within one standard deviation of the process mean.Why might you deem the process to be "out of control"?

Accepted Answer

The answer of A full day's quality control tests (24...

Question 5

Suppose an X-bar chart has a centerline of 10.0 and upper and lower control limits of 16.0 and 4.0 respectively.The sample mean values over the next eight periods are 10.2, 9.3, 11.4, 11.8, 12.7, 14.2, 13.8, and 15.2.Would you conclude that the process is in control during this time frame? If not, which period(s) indicate an out of control process, and which tests are violated?

Accepted Answer

The answer of Suppose an X-bar chart has a centerline...

Question 6

If a process is to be sampled once each hour, the precise time within the hour:

Accepted Answer

A)  should be the same each hour of operation.
B)  should change with shift changes.
C)  should be determined randomly.
D)  should be incremented on a constant basis.

Question 7

Control limits for the mean are symmetrical around $\bar { \bar { X } }$ , and control limits for the range around $\bar { R }$ are also symmetrical.

Accepted Answer

A) True 
 B)False

Question 8

Deming's points discourage inspection for quality control.

Accepted Answer

A) True 
 B)False

Question 9

Under what conditions can control test 7 (8 consecutive points outside plus or minus one standard deviation) be applied to the X and R_m control charts for single item sampling?

Accepted Answer

The answer of Under what conditions can control test 7...

Question 10

Six Sigma refers to plus or minus three standard deviations.

Accepted Answer

A) True 
 B)False

Question 11

Both Deming's 14 points and the Six Sigma concept promote risk taking.

Accepted Answer

A) True 
 B)False

Question 12

In establishing control limits for $\bar { X }$ charts:

Accepted Answer

A)    Rˉ\bar { R }Rˉ  is used in the estimation of ?.
B)  a two-standard deviation range is typical.
C)   is the center line.
D)  the range between limits is independent of sample size.

Question 13

Which of the following is not a reason to prefer single-item sampling to multi-item sampling?

Accepted Answer

A)  Attributes, not measurements, are being evaluated.
B)  Items sampled are necessarily destroyed.
C)  Process output is known to be relatively homogeneous.
D)  The cost of sampling each item is extremely high.

Question 14

Which two groups can control process variation?

Accepted Answer

The answer of Which two groups can control process variation?...

Question 15

Fifteen random samples of size four yield the following statistics:Sample $\bar { X }$ R Sample $\bar { X }$ R Sample $\bar { X }$ R
$\begin{array} { c c c c c c c c c } 
1 & 331 & 8 & 6 & 333 & 4 & 11 & 332 & 6 \
2 & 333 & 5 & 7 & 332 & 13 & 12 & 335 & 7 \
3 & 335 & 8 & 8 & 331 & 5 & 13 & 330 & 7 \
4 & 337 & 7 & 9 & 334 & 6 & 14 & 330 & 5 \
5 & 336 & 9 & 10 & 332 & 9 & 15 & 334 & 6
\end{array}$
For these data, determine the upper and lower control limits for the $\bar { X }$ and R charts.

Accepted Answer

The answer of Fifteen random samples of size four yield...

Question 16

A bowling alley checks the timing of the ball returns daily for four lanes.The times are given in seconds.Create X-bar and R charts.Is the process in control?$$\begin{array} { c c c c c } 
\text { day\ allay \# } & \mathbf { 1 } & \mathbf { 2 } & \mathbf { 3 } & \mathbf { 4 } \
\mathbf { 1 } & 15 & 17 & 15 & 17 \
\mathbf { 2 } & 17 & 16 & 18 & 21 \
\mathbf { 3 } & 16 & 15 & 14 & 16 \
\mathbf { 4 } & 19 & 16 & 19 & 18 \
\mathbf { 5 } & 15 & 17 & 15 & 20 \
\mathbf { 6 } & 15 & 14 & 14 & 19 \
\mathbf { 7 } & 16 & 18 & 17 & 18 \
\mathbf { 8 } & 18 & 15 & 18 & 20 \
\mathbf { 9 } & 15 & 16 & 15 & 17 \
\mathbf {10} & 16 & 16 & 16 & 21
\end{array}$$

Accepted Answer

The answer of A bowling alley checks the timing of...

Question 17

According to the central limit theorem, sample values follow a normal distribution.

Accepted Answer

A) True 
 B)False

Question 18

Process variation, the measurable change in the output of a process:

Accepted Answer

A)  is always subject to elimination.
B)  is not management's responsibility.
C)  may be uncontrollable.
D)  generates output of unacceptable quality.

Question 19

Walter Shewhart, the developer of control charts, believed quality is associated with consistency of performance.

Accepted Answer

A) True 
 B)False

Question 20

Additional tests, beyond observing sample data points falling within the specified control limits, are available.None of these additional tests evaluate:

Accepted Answer

A)  consecutive values on the same side of the centerline.
B)  consecutive increasing or decreasing values.
C)  consecutive oscillating values.
D)  consecutive constant values.

Exam 11: Quality Management Models

Why are there eight tests for control for $\bar { X }$ charts but only four for R charts?

Sources of random error in monitoring a production process for quality control purposes include:

A full day's quality control tests (24 points) all fall within one standard deviation of the process mean.Why might you deem the process to be "out of control"?

If a process is to be sampled once each hour, the precise time within the hour:

Control limits for the mean are symmetrical around $\bar { \bar { X } }$ , and control limits for the range around $\bar { R }$ are also symmetrical.

Deming's points discourage inspection for quality control.

Under what conditions can control test 7 (8 consecutive points outside plus or minus one standard deviation) be applied to the X and R_m control charts for single item sampling?

Six Sigma refers to plus or minus three standard deviations.

Both Deming's 14 points and the Six Sigma concept promote risk taking.

In establishing control limits for $\bar { X }$ charts:

Which of the following is not a reason to prefer single-item sampling to multi-item sampling?

Which two groups can control process variation?

According to the central limit theorem, sample values follow a normal distribution.

Process variation, the measurable change in the output of a process:

Walter Shewhart, the developer of control charts, believed quality is associated with consistency of performance.

Additional tests, beyond observing sample data points falling within the specified control limits, are available.None of these additional tests evaluate:

Exam 11: Quality Management Models

Why are there eight tests for control for Xˉ\bar { X }Xˉ charts but only four for R charts?

Sources of random error in monitoring a production process for quality control purposes include:

A full day's quality control tests (24 points) all fall within one standard deviation of the process mean.Why might you deem the process to be "out of control"?

If a process is to be sampled once each hour, the precise time within the hour:

Control limits for the mean are symmetrical around Xˉˉ\bar { \bar { X } }Xˉˉ , and control limits for the range around Rˉ\bar { R }Rˉ are also symmetrical.

Deming's points discourage inspection for quality control.

Under what conditions can control test 7 (8 consecutive points outside plus or minus one standard deviation) be applied to the X and Rm control charts for single item sampling?

Six Sigma refers to plus or minus three standard deviations.

Both Deming's 14 points and the Six Sigma concept promote risk taking.

In establishing control limits for Xˉ\bar { X }Xˉ charts:

Which of the following is not a reason to prefer single-item sampling to multi-item sampling?

Which two groups can control process variation?

According to the central limit theorem, sample values follow a normal distribution.

Process variation, the measurable change in the output of a process:

Walter Shewhart, the developer of control charts, believed quality is associated with consistency of performance.

Additional tests, beyond observing sample data points falling within the specified control limits, are available.None of these additional tests evaluate:

Why are there eight tests for control for $\bar { X }$ charts but only four for R charts?

Control limits for the mean are symmetrical around $\bar { \bar { X } }$ , and control limits for the range around $\bar { R }$ are also symmetrical.

Under what conditions can control test 7 (8 consecutive points outside plus or minus one standard deviation) be applied to the X and R_m control charts for single item sampling?

In establishing control limits for $\bar { X }$ charts: