Question 1

Those causes of variation which are small in magnitude are:
A) special causes
B) assignable causes
C) chance causes
D) fluctuating causes

Accepted Answer

Chance causes refer to natural or inherent variation in a process that is unpredictable and random. These causes are often small in magnitude and can be present even in a stable process. Special causes (A) and assignable causes (B) are specific sources of variation that can be identified and eliminated to improve a process. Fluctuating causes (D) is not a commonly used term in the context of process variation.

Question 2

Which of the following subgroup sizes for an X and R chart would not be used?
A) 1
B) 4
C) 5
D) 2

Accepted Answer

A subgroup size of 1 would not be used because there would be no range in this case and the control limits cannot be calculated.

Question 3

If only one measurement can be taken at a time, the chart to use is called:
A) moving average
B) trend
C) median
D) sun

Accepted Answer

A moving average chart is used when only one measurement can be taken at a time. It helps in smoothing out short-term fluctuations and highlighting longer-term trends or cycles.

Question 4

A user friendly chart for the operator to use is called:
A) moving average
B) median
C) trend
D) all of the above

Accepted Answer

The answer of A user friendly chart for the operator...

Question 5

The process spread is the same as the:
A) tolerance
B) quality spread
C) index
D) process capability

Accepted Answer

The process spread is a measure of the variation in a process and is directly related to process capability (the ability of a process to consistently produce output within a certain range of specifications). Therefore, the correct answer is D - process capability. Choices A (tolerance) and B (quality spread) are related to the range of acceptable performance, but they do not specifically pertain to the variation in the process. Choice C (index) is too general and does not specifically relate to the concept of process spread.

Question 6

Given the following range readings for 25 subgroups of size four, determine the process capability. $\begin{array}{cc}
\text { Subgroup } & \text { R } \
1 & 3.2 \
2 & 3.8 \
3 & 3.6\
⋅&⋅\square\
⋅&⋅\square\
⋅&⋅\
24 & 3.6 \
25 & 3.4\&\square=90.0
\end{array}$

Accepted Answer

The answer of Given the following range readings for 25...

Question 7

Which of the following is the name of an out-of- control pattern?
A) assignable
B) causal
C) shift or jump
D) a and b

Accepted Answer

A shift or jump is considered an out-of-control pattern because it indicates a sudden, unexplained change in the process mean. Assignable causes and causal factors refer to specific, identifiable reasons for variation and are within the control of the process. Therefore, they are not considered out-of-control patterns on their own.

Question 8

Which of the following subgroup sizes of an X and R chart would most likely be used for costly testing?
A) 6
B) 4
C) 5
D) 2

Accepted Answer

For costly testing scenarios, smaller subgroup sizes are preferred to minimize the number of tests needed. A subgroup size of 2 is the smallest practical size that still allows for the calculation of range (R), making it the most likely choice for costly testing situations.

Question 9

When using the X chart the central limit theorem is the basis for a sample size of:
A) 2
B) 3
C) 4
D) 5

Accepted Answer

The X chart is typically used for monitoring the process mean of a variable. According to the central limit theorem, for a large enough sample size (typically n>30), the distribution of sample means will be approximately normal. Thus, a larger sample size would result in a better estimate of the actual mean and a more accurate X chart. Since the question does not provide any additional information about the process or the variable being monitored, it is safest to assume that a sample size of 4 may not be sufficient to rely on the central limit theorem. Therefore, the best choice would be to select a larger sample size, such as C) 4.

Question 10

An s chart might be used as a measure of dispersion rather than an R chart because it is:
A) easier to understand
B) more sensitive to variations
C) more accurate
D) b and c

Accepted Answer

The answer of An s chart might be used as...

Question 11

The specifications for an electronic device are 3.00 ± 0.10 amps. If the standard deviation is 0.02, what is the capability index?

Accepted Answer

The answer of The specifications for an electronic device are...

Question 12

Those causes of variation which are large in magnitude and are not part of the normal variation are:
A) stable causes
B) chance causes
C) assignable causes
D) fluctuating causes

Accepted Answer

Assignable causes are those which are large in magnitude and can be identified, corrected, and eliminated to reduce the variation in a process. Stable causes are typically normal variations that are consistent over time, whereas chance or fluctuating causes are random variations that occur naturally and cannot be controlled. Therefore, the best choice is C - assignable causes.

Question 13

Using the data below, determine the trial central line and trial control limits for the X-bar chart. Subgroup size is 5. For the R chart, the trial central line is 0.11, the UCL is 0.23, and LCL is 0. Note not all of the subgroups are included in the data;however, the sums are correct. $$\begin{array} { | c | c | c | } 
\hline \text { Subgroup } & \text { X-bar } & \text { R } \
\hline 1 & 2.08 & .05 \
\hline 2 & 2.09 & .24 \
\hline 3 & 2.08 & .10 \
\hline \bullet & \bullet & \bullet \
\hline \bullet & \bullet & \bullet \
\hline \bullet & \bullet & \bullet \
\hline 25 & 2.09 & .11 \
\hline & ^{\mathrm { TM } }= 52.00 & ^{\mathrm { TM } }= 2.75 \
\hline
\end{array}$$

Accepted Answer

The answer of Using the data below, determine the trial...

Question 14

An R chart is not accurate above a sample size of:
A) 5
B) 7
C) 10
D) 15

Accepted Answer

An R chart is not accurate above a sample size of 10 because it becomes difficult to distinguish between natural variation and process variation. At this point, it is recommended to use a control chart based on averages (X-bar chart) instead of R-chart. Therefore, option C is the correct choice.

Question 15

Which of the following is a source of variation:
A) materials
B) piece-to-piece
C) chance
D) none of these

Accepted Answer

The answer of Which of the following is a source...

Question 16

The numerator of the capability index equation is the:
A) tolerance
B) capability ratio
C) process spread
D) none of the above

Accepted Answer

The numerator of the capability index equation is the tolerance, which is the range of acceptable values defined by the specification limits.

Question 17

Of the following, the capability index that is most desirable is:
A) 1.00
B) 1.50
C) 0.75
D) 0.30

Accepted Answer

A capability index measures how well a process can meet its specification limits. The higher the index, the more capable the process is. A capability index of 1.50 indicates a process that is performing significantly better than one with a capability index of 1.00, 0.75, or 0.30, making it the most desirable option.

Quiz 6: Control Charts for Variables

Those causes of variation which are small in magnitude are:

Which of the following subgroup sizes for an X and R chart would not be used?

If only one measurement can be taken at a time, the chart to use is called:

A user friendly chart for the operator to use is called:

The process spread is the same as the:

Given the following range readings for 25 subgroups of size four, determine the process capability. $\begin{array}{cc}\text { Subgroup } & \text { R } \\1 & 3.2 \\2 & 3.8 \\3 & 3.6\\⋅&⋅\square\\⋅&⋅\square\\⋅&⋅\\24 & 3.6 \\25 & 3.4\\&\square=90.0\end{array}$

Which of the following is the name of an out-of- control pattern?

Which of the following subgroup sizes of an X and R chart would most likely be used for costly testing?

When using the X chart the central limit theorem is the basis for a sample size of:

An s chart might be used as a measure of dispersion rather than an R chart because it is:

The specifications for an electronic device are 3.00 ± 0.10 amps. If the standard deviation is 0.02, what is the capability index?

Those causes of variation which are large in magnitude and are not part of the normal variation are:

An R chart is not accurate above a sample size of:

Which of the following is a source of variation:

The numerator of the capability index equation is the:

Of the following, the capability index that is most desirable is: