Deck 9: Quality Control and Improvement

Question 1

Suppose that you have taken 30 samples of 200 units each and calculated the proportion defective as p = .075.What is the upper control limit for a p-chart (rounded to 4 decimals)?

A).2192
B).0191
C).1309
D).7500

Answer 1

C

Question 2

A Pareto chart:

A)Shows causes and effects of quality problems
B)Shows the importance of the various types of defects that have been found
C)Is not useful when first studying a quality problem
D)Has both upper and lower specification limits

Answer 2

B

Question 3

A process control chart:

A)Assumes that 99.74% of random variations observed will fall within an upper and lower limit
B)Represents upper and lower control limits set at $\pm$ 2 standard deviations from the center line
C)Separates the assignable cause of variation from the common cause of variation
D)Assigns causes of variation to operator,machine,or material
E)Both a and c

Answer 3

Both a and c

Question 4

Suppose that a process is in a state of control and we have the following information for a human weights measurement study. Average weight of males in the study = 150 lbs.
Average range of the male weights = 100 lbs.
A₂ = .577
D₃ = 0
D₄ = 2.115
What is the upper control limit for the average (mean)chart?

A)207.7 lbs
B)92.3 lbs
C)361.5 lbs
D)175 lbs

Question 5

The appearance of a TV cabinet that is not satisfactory is an example of:

A)Variable measurement
B)Mean chart
C)Range chart
D)Attribute measurement
E)None of the above

Question 6

Sampling inspection by attributes:

A)Means each item sampled is classified as defective or not defective based on quality standards
B)Could be used together with process control and variable measurement as part of a quality control system
C)Utilizes a discrete scale of measurement
D)a and c
E)a,b,and c

Question 7

Which of the following is/are assumptions of process control?

A)Random variability cannot be eliminated unless the process is redesigned.
B)Common causes represent random variability.
C)Production processes are not usually found in a state of control.
D)Only a and c
E)a,b,and c

Question 8

Using the information from question 8,what is the upper control limit for the range chart?

A)57.7 lbs
B)211.5 lbs
C)317.25 lbs
D)86.55 lbs

Question 9

For which of the following would a p-chart be used?

A)Monitor dispersion in sample data
B)Measure the number of defects per unit
C)Measure the central tendency
D)Measure the variability
E)Measure the fraction defective

Question 10

Which of the following statements about process capability is accurate?

A)C_pk is a better measure of process capability than C_p.
B)C_p is exactly equal to C_pk when the mean is centered in the specification limits.
C)Given the same process,C_pk is always less than or equal to C_p.
D)All of the above are accurate.

Question 11

A cause-and-effect diagram:

A)Identifies common causes of quality defects on its spines
B)Is often used in conjunction with a Pareto chart
C)Could be used to facilitate continuous improvement
D)Is also called a fishbone diagram
E)All of the above are true

Question 12

Which of the following statements about process quality control is NOT true?

A)Assignable cause variation is also referred as special cause variation
B)An observation outside the control limits is an example of a special cause of variation
C)Common cause variation can be eliminated from the process by removing the potential causes
D)The control limits will include 99.74% of the population under the normal probability distribution assuming that the process is in control
E)None of the above

Question 13

A complete system of quality control:

A)Is defined by critical control points,inspectors,measurements,costs,and other considerations
B)Involves a zero defects philosophy
C)Requires a continuous scale for measurement of defects
D)Must include both variable and attribute measurements

Question 14

The second step in designing a quality control system is to decide on:

A)The amount of inspection to use
B)Who should do the inspection
C)The type of measurement to be used
D)The critical points in each of the processes where inspection is needed
E)Whether to certify suppliers

Question 15

The Chair of the Quality Department at Motorola University wants to construct a p-chart for determining whether the four faculty members teaching the course are under control concerning the number of students who fail in the course.Accordingly,the Chair sampled 500 final grades from last year for each instructor,and computed the number of failures per instructor as 13,11,0,and 16 respectively.Compute the upper and lower standard control limits for this chart (rounded to 4 decimals).

A)0.9500 and 0.0500
B)0.0600 and 0.1400
C)0.0388 and 0.0012
D)0.1400 and 0.0000
E)None of the above

Question 16

Which of the following quality control sample statistics indicates a quality characteristic that is an attribute?

A)Mean
B)Proportion
C)Variance
D)Standard deviation
E)Range

Question 17

The ability of the process to meet,or exceed,its specifications can be determined by:

A)Pareto charts
B)Cause-and-effect diagrams
C)Histograms
D)C_p index
E)Variable control charts

Question 18

Using the same data as in question 10,what is the lower control limit for a p-chart (rounded to 4 decimals)?

A).0750
B).0191
C).0000
D).0692

Question 19

Which of the following techniques are used for continuous improvement?

A)Pareto charts
B)Cause-and-effect diagrams
C)Process capability charts
D)Only a and b
E)a,b,and c

Question 20

Which of the following statements is NOT true about six sigma quality?

A)Six sigma results in 3.4 ppm defects
B)Six sigma is equivalent to a process capability of C_pk = 1.5
C)Six sigma corresponds to 3 standard deviations on either side of the mean
D)Six sigma can be applied to administrative and service processes as well
E)Motorola invented the term "six sigma quality" in the mid-80s

Question 21

The C_p measure requires the process to be centered for an accurate measure of process capability.

Question 22

List and explain the five steps of the DMAIC process.

Question 23

We need information only regarding the central tendency of the process while examining a continuous process.

Question 24

Lean and six sigma projects both use 5-step processes.

Question 25

Surveys indicate that p charts are used more frequently than average (mean)and range charts are used.

Question 26

The quality tool that shows the relationship between two variables is a histogram.

Question 27

Six sigma efforts are aimed at eliminating waste.

Question 28

The seven tools of quality control are equally applicable to both manufacturing and service industries.

Question 29

"A production process delivers large amount of scrap products.Top management has discovered that improper machine maintenance is the reason behind this failure."
The above statement is an example of a special cause of variation.

Question 30

In process capability analysis,the standard deviation ( $\sigma$ )refers to the standard deviation of the samples taken from the control chart.

Question 31

Lean projects are usually simpler than six sigma projects.

Question 32

Attribute control occurs when the product characteristic is measured on a continuous scale.

Question 33

A machining process is capable of producing a component with an average specification of 5 inches and a process standard deviation of 0.1 inch.Suppose the customer accepts the component as long as it falls between 4.8 inches and 5.2 inches,then the process capability is:

A)1.333
B)1.5
C)0.667
D)1.0
E)4.0

Question 34

Six sigma projects are typically managed by full-time black belts.

Question 35

If failure costs were very high,a company would still use inspection.

Question 36

There are two indicators of a process shift-points outside the control limits and an upward or downward trend in the process average.