Question 1

Using three sigma control limits (rather than two sigma limits)tends to have what impact on error probabilities?

Accepted Answer

A) Increase the Type II and decrease the Type I. 
B) Decrease the Type II and increase the Type I. 
C) Decrease the Type I and Type II. 
D) Increase the Type I and Type II. 
E) Have little or no impact. 
A) Increase the Type II and decrease the Type I. 
B) Decrease the Type II and increase the Type I. 
C) Decrease the Type I and Type II. 
D) Increase the Type I and Type II. 
E) Have little or no impact. A

Question 2

Studies on a machine that molds plastic water pipe indicate that when it is injecting 25 mm diameter pipe,the process standard deviation is 0.50 mm.The 25 mm pipe has a specification of 25 mm plus or minus 1.0 mm.What is the process capability index (Cp)?

Accepted Answer

A) 0.50 
B) 0.67 
C) 1.00 
D) 2.00 
A) 0.50 
B) 0.67 
C) 1.00 
D) 2.00 B

Question 3

Given the following process control data for a normally distributed quality variable (three samples of size four each):
   If the process is known to have a mean of 15 and a standard deviation of 3,what are the three sigma upper and lower control limits for an x-bar chart?

Accepted Answer

15 Lower limit = 10.5 Upper limit = 19.5

Question 4

A Quality Analyst wants to construct a control chart for determining whether three machines,all producing the same product,are under control with regard to a particular quality variable.Accordingly,he sampled four units of output from each machine,with the following results:   Using the factors for three sigma control limits,what are the x-bar chart upper and lower control limits?

Accepted Answer

A) 24.33 and 15.67 
B) 23.29 and 16.71 
C) 23.5 and 16.5 
D) 23.16 and 16.84 
E) 24.42 and 17.67 
A) 24.33 and 15.67 
B) 23.29 and 16.71 
C) 23.5 and 16.5 
D) 23.16 and 16.84 
E) 24.42 and 17.67

Question 5

Given the following process control data for a quality attribute (three samples of size 400 each):
   What is the sample proportion of defectives for sample #1? #2? #3?

Accepted Answer

The answer of Given the following process control data for...

Question 6

The optimum level of inspection for quality control is where the:

Accepted Answer

A) cost of inspection is minimum. 
B) cost of passing defectives is minimum. 
C) total cost of inspection and passing defectives is maximum. 
D) total cost of inspection and passing defectives is minimum. 
E) difference in inspection and defectives costs is minimum. 
A) cost of inspection is minimum. 
B) cost of passing defectives is minimum. 
C) total cost of inspection and passing defectives is maximum. 
D) total cost of inspection and passing defectives is minimum. 
E) difference in inspection and defectives costs is minimum.

Question 7

Four samples of three observations each have been taken,with actual measurements (in centimetres)shown below.Construct three sigma mean and range charts,and determine if corrective action is needed.
 11eab92b_c48d_2c65_99e6_039f93955d70

Accepted Answer

@#IMG-DLM&_TB6896_00 @#IMG-DLM&_TB6896_00 Grand mean = 12.05

Question 8

Given the following process control data for a quality attribute (three samples of size 400 each):
   If the process is known to produce 11 percent defectives on average,what are the upper and lower control limits for an alpha risk of .10? .05? .01?

Accepted Answer

.1357 and

Question 9

Design specifications are equivalent to control limits.

Accepted Answer

A) True 
 B)False

Question 10

The output of a process may not conform to design specifications even though the process may be statistically "in control".

Accepted Answer

A) True 
 B)False

Question 11

The range chart (R-chart)is most likely to detect a change in:

Accepted Answer

A) proportion. 
B) mean. 
C) number defective. 
D) process variability. 
E) sample size. 
A) proportion. 
B) mean. 
C) number defective. 
D) process variability. 
E) sample size.

Question 12

Variation in a sample statistic collected from a process may be either random variation or assignable variation.

Accepted Answer

A) True 
 B)False

Question 13

For a process to be capable,it must have a capability ratio of at least 1.00.A ratio of 1.00 implies that what percent of the output of a process can be expected to be within the design specification limits?

Accepted Answer

A) 66.67% 
B) 73.33% 
C) 95.54% 
D) 99.74% 
E) 100% 
A) 66.67% 
B) 73.33% 
C) 95.54% 
D) 99.74% 
E) 100%

Question 14

The term "2 sigma limits" in the context of a control chart refers to the variability of the:

Accepted Answer

A) process. 
B) population. 
C) sample. 
D) sampling distribution. 
A) process. 
B) population. 
C) sample. 
D) sampling distribution.

Question 15

Quality control efforts that occur during production are referred to as statistical process control.

Accepted Answer

A) True 
 B)False

Question 16

Assignable variation is variation due to a specific cause,such as tool wear.

Accepted Answer

A) True 
 B)False

Question 17

Control limits and process variability are directly related.

Accepted Answer

A) True 
 B)False

Question 18

The frequency and quantity of inspection depends primarily on the cost of inspection.

Accepted Answer

A) True 
 B)False

Question 19

Given the following process control data for a quality attribute (three samples of size 400 each):
   If the process is known to produce 11 percent defectives on average,what is the alpha risk (probability of Type I error)for upper and lower control limits of .1256 and .0944 respectively? .1412 and .0788? .1568 and .0632?

Accepted Answer

The answer of Given the following process control data for...

Question 20

Sample range control charts are used to measure shifts in the process mean.

Accepted Answer

A) True 
 B)False

Exam 15: Statistical Quality Control

Using three sigma control limits (rather than two sigma limits)tends to have what impact on error probabilities?

Studies on a machine that molds plastic water pipe indicate that when it is injecting 25 mm diameter pipe,the process standard deviation is 0.50 mm.The 25 mm pipe has a specification of 25 mm plus or minus 1.0 mm.What is the process capability index (Cp)?

Given the following process control data for a normally distributed quality variable (three samples of size four each): If the process is known to have a mean of 15 and a standard deviation of 3,what are the three sigma upper and lower control limits for an x-bar chart?

Given the following process control data for a quality attribute (three samples of size 400 each): What is the sample proportion of defectives for sample #1? #2? #3?

The optimum level of inspection for quality control is where the:

Four samples of three observations each have been taken,with actual measurements (in centimetres)shown below.Construct three sigma mean and range charts,and determine if corrective action is needed. 11eab92b_c48d_2c65_99e6_039f93955d70

Given the following process control data for a quality attribute (three samples of size 400 each): If the process is known to produce 11 percent defectives on average,what are the upper and lower control limits for an alpha risk of .10? .05? .01?

Design specifications are equivalent to control limits.

The output of a process may not conform to design specifications even though the process may be statistically "in control".

The range chart (R-chart)is most likely to detect a change in:

Variation in a sample statistic collected from a process may be either random variation or assignable variation.

For a process to be capable,it must have a capability ratio of at least 1.00.A ratio of 1.00 implies that what percent of the output of a process can be expected to be within the design specification limits?

The term "2 sigma limits" in the context of a control chart refers to the variability of the:

Quality control efforts that occur during production are referred to as statistical process control.

Assignable variation is variation due to a specific cause,such as tool wear.

Control limits and process variability are directly related.

The frequency and quantity of inspection depends primarily on the cost of inspection.

Sample range control charts are used to measure shifts in the process mean.

Introduction to Operations Management

Competitiveness, strategic Planning, and Productivity

Demand Forecasting

Product Design

Reliability

Strategic Capacity Planning

Decision Analysis

Process Design and Facility Layout

Linear Programming

Workjob Design

Learning Curves

Location Planning and Analysis

the Transportation Model

Management of Quality

Acceptance Sampling

Supply Chain Management

Inventory Management

Aggregate Operations Planning and Master Scheduling

Material Requirements Planning and Enterprise Resource Planning

Just-In-Time and Lean Production

Maintenance

Job and Staff Scheduling

Project Management

Waiting-Line Analysis

Simulation

Filters