Question 1

According to the text, the most common choice of limits for control charts is usually

Accepted Answer

A)  ± 1 standard deviation 
B)  ± 2 standard deviations 
C)  ± 3 standard deviations 
D)  ± 3 standard deviations for means and ± 2 standard deviations for ranges 
E)  none of the above 
A)  ± 1 standard deviation 
B)  ± 2 standard deviations 
C)  ± 3 standard deviations 
D)  ± 3 standard deviations for means and ± 2 standard deviations for ranges 
E)  none of the above C

Question 2

The __________ is a quality control chart used to control the number of defects per unit of output.

Accepted Answer

c-chart

Question 3

A bank's manager has videotaped 20 different teller transactions to observe the number of mistakes being made. Ten transactions had no mistakes, five had one mistake and five had two mistakes. Compute proper control limits at the 90% confidence level.

Accepted Answer

A c-chart should be used, and from Table S6.2, the z-value = 1.65.
The mean c-bar = [10(0) + 5(1) + 5(2)]/20 = 0.75.
UCLc = 0.75 + 1.65 $\sqrt { 0.75 }$ = 2.18
LCLc = 0.75 - 1.65 $\sqrt { 0.75 }$ = -0.68 (or 0)

Question 4

The purpose of process control is to detect when natural causes of variation are present.

Accepted Answer

A) True 
 B)False

Question 5

At your first job out of college you have been assigned to the production of bottled 20 oz. soda.
The process has upper and lower limits of 20.5 and 19.5 oz, respectively, with a mean of 19.8 oz
and standard deviation of .3 oz. Your manager has requested the process produce no more than 3.4
defects per 1 million bottles produced. Calculate Cpk and then determine if the process is capable
or if you should be looking for assignable variation.

Accepted Answer

Cpk = minimum ( (20.5-19.8)/(3*.3),(19.8

Question 6

A quality analyst wants to construct a sample mean chart for controlling a packaging process. He knows from past experience that when the process is operating as intended, packaging weight is normally distributed with a mean of twenty ounces, and a process standard deviation of two ounces. Each day last week, he randomly selected four packages and weighed each. The data from that activity appears below.
 $$\begin{array} { | l | l | l | l | l | } 
\hline& { \text { Weight } } \
\hline \text { Day } & \text { Package 1 } & \text { Package 2 } & \text { Package 3 } & \text { Package 4 } \
\hline \text { Monday } & 23 & 22 & 23 & 24 \
\hline \text { Tuesday } & 23 & 21 & 19 & 21 \
\hline \text { Wednesday } & 20 & 19 & 20 & 21 \
\hline \text { Thursday } & 18 & 19 & 20 & 19 \
\hline \text { Friday } & 18 & 20 & 22 & 20 \
\hline
\end{array}$$ 
(a) If he sets an upper control limit of 21 and a lower control limit of 19 around the target value of twenty ounces, what is the probability of concluding that this process is out of control when it is actually in control?
(b) With the UCL and LCL of part a, what do you conclude about this process-is it in control?

Accepted Answer

(a) These control limits are one standar

Question 7

The Central Limit Theorem

Accepted Answer

A)  is the theoretical foundation of the c-chart 
B)  states that the average of assignable variations is zero 
C)  allows managers to use the normal distribution as the basis for building some control charts 
D)  states that the average range can be used as a proxy for the standard deviation 
E)  controls the steepness of an operating characteristic curve 
A)  is the theoretical foundation of the c-chart 
B)  states that the average of assignable variations is zero 
C)  allows managers to use the normal distribution as the basis for building some control charts 
D)  states that the average range can be used as a proxy for the standard deviation 
E)  controls the steepness of an operating characteristic curve

Question 8

A car mechanic is thinking of guaranteeing customers that an oil change will take no more than 15 minutes with a 99.73% confidence level. He takes a few samples of size 5 and finds the process mean to be 13 minutes with a standard deviation of .2 minutes and average sample range of 1.2 minutes. Find the A₂, D₄, and D₃ values and use them to compute the upper and lower limits for an x-bar chart. Use the upper limit to determine if the mechanic can offer a 15 minute guarantee. Assume the mechanic plots the samples on the x-bar control chart and finds the process is in control, is there anything else the mechanic is missing to ensure the process is in control?

Accepted Answer

From Table S6.1
A₂ = .577
D₄ = 2.115
D₃

Question 9

The type of inspection that classifies items as being either good or defective is

Accepted Answer

A)  variable inspection 
B)  attribute inspection 
C)  fixed inspection 
D)  all of the above 
E)  none of the above 
A)  variable inspection 
B)  attribute inspection 
C)  fixed inspection 
D)  all of the above 
E)  none of the above

Question 10

Cartons of Plaster of Paris are supposed to weigh exactly 32 oz. Inspectors want to develop process control charts. They take ten samples of six boxes each and weigh them. Based on the following data, compute the lower and upper control limits and determine whether the process is in control.
 $$\begin{array} {| l | l l |} 
\hline \text { Sample } & \text { Mean } & \text { Range } \
\hline 1 & 33.8 & 1.1 \
\hline 2 & 34.6 & 0.3 \
\hline 3 & 34.7 & 0.4 \
\hline 4 & 34.1 & 0.7 \
\hline 5 & 34.2 & 0.3 \
\hline 6 & 34.3 & 0.4 \
\hline 7 & 33.9 & 0.5 \
\hline 8 & 34.1 & 0.8 \
\hline 9 & 34.2 & 0.4 \
\hline 10 & 34.4 & 0.3 \
\hline
\end{array}$$

Accepted Answer

The answer of Cartons of Plaster of Paris are supposed...

Question 11

Which of the following statements on acceptance sampling is true?

Accepted Answer

A)  Acceptance sampling draws samples from a population of items, tests the sample, and accepts the entire population if the sample is good enough, and rejects it if the sample is poor enough. 
B)  The sampling plan contains information about the sample size to be drawn and the critical acceptance or rejection numbers for that sample size. 
C)  The steeper an operating characteristic curve, the better its ability to discriminate between good and bad lots. 
D)  All of the above are true. 
E)  All of the above are False. 
A)  Acceptance sampling draws samples from a population of items, tests the sample, and accepts the entire population if the sample is good enough, and rejects it if the sample is poor enough. 
B)  The sampling plan contains information about the sample size to be drawn and the critical acceptance or rejection numbers for that sample size. 
C)  The steeper an operating characteristic curve, the better its ability to discriminate between good and bad lots. 
D)  All of the above are true. 
E)  All of the above are False.

Question 12

A city police chief decides to do an annual review of the police department by checking the number of monthly complaints. If the total number of complaints in each of the 12 months were 15, 18, 13, 12, 16, 20, 5, 10, 9, 11, 8, and 3 and the police chief wants a 90% confidence level, are the complaints in control?

Accepted Answer

From Table S6.2 z=1.65
c-bar = (15+18+13

Question 13

An acceptance sampling plan must define "good lots" and "bad lots" and specify the risk level associated with each one.

Accepted Answer

A) True 
 B)False

Question 14

A p-chart is appropriate to plot the number of typographic errors per page of text.

Accepted Answer

A) True 
 B)False

Question 15

Which of the following statements about acceptance sampling is true?

Accepted Answer

A)  The steeper an OC curve, the better it discriminates between good and bad lots. 
B)  Acceptance sampling removes all defective items. 
C)  Acceptance sampling of incoming lots is replacing statistical process control at the supplier. 
D)  Acceptance sampling occurs continuously along the assembly line. 
E)  All of the above are true. 
A)  The steeper an OC curve, the better it discriminates between good and bad lots. 
B)  Acceptance sampling removes all defective items. 
C)  Acceptance sampling of incoming lots is replacing statistical process control at the supplier. 
D)  Acceptance sampling occurs continuously along the assembly line. 
E)  All of the above are true.

Question 16

A lot that is accepted by acceptance sampling is certified to be free of defects.

Accepted Answer

A) True 
 B)False

Question 17

Examine the Statistical Process Control outputs below. Answer the following questions.
a. What is the sample size?
b. What is the number of samples?
c. What is the mean of sample 8; what is the range of sample 10?
d.. Is this process in control?
 Explain--a simple Yes or No is insufficient.
e. What additional steps should the quality assurance team take?

Accepted Answer

The sample size is 4; ten samples were t

Question 18

A small, independent amusement park collects data on the number of cars with out-of-state license plates. The sample size is fixed at n=25 each day. Data from the previous 10 days indicate the following number of out-of-state license plates:
 $$\begin{array} { | c | c | } 
\hline \text { Day } & \begin{array} { c } 
\text { Out-of-state } \
\text { Plates }
\end{array} \
\hline 1 & 6 \
\hline 2 & 4 \
\hline 3 & 5 \
\hline 4 & 7 \
\hline 5 & 8 \
\hline 6 & 3 \
\hline 7 & 4 \
\hline 8 & 5 \
\hline 9 & 3 \
\hline 10 & 11 \
\hline
\end{array}$$ 
(a) Calculate the overall proportion of "tourists" (cars with out-of-state plates) and the standard deviation of proportions.
(b) Using ± 3σ limits, calculate the LCL and UCL for these data.
(c) Is the process under control?
 Explain.

Accepted Answer

(a) p-bar is 56/250 = 0.224; the standar

Question 19

The causes of variation in statistical process control are

Accepted Answer

A)  cycles, trends, seasonality, and random variations 
B)  producer's causes and consumer's causes 
C)  mean and range 
D)  natural causes and assignable causes 
E)  Type I and Type II 
A)  cycles, trends, seasonality, and random variations 
B)  producer's causes and consumer's causes 
C)  mean and range 
D)  natural causes and assignable causes 
E)  Type I and Type II

Question 20

A(n) __________ is a graph that describes how well an acceptance plan discriminates between good and bad lots.

Accepted Answer

OC or oper

According to the text, the most common choice of limits for control charts is usually

The __________ is a quality control chart used to control the number of defects per unit of output.

A bank's manager has videotaped 20 different teller transactions to observe the number of mistakes being made. Ten transactions had no mistakes, five had one mistake and five had two mistakes. Compute proper control limits at the 90% confidence level.

The purpose of process control is to detect when natural causes of variation are present.

The Central Limit Theorem

The type of inspection that classifies items as being either good or defective is

Which of the following statements on acceptance sampling is true?

An acceptance sampling plan must define "good lots" and "bad lots" and specify the risk level associated with each one.

A p-chart is appropriate to plot the number of typographic errors per page of text.

Which of the following statements about acceptance sampling is true?

A lot that is accepted by acceptance sampling is certified to be free of defects.

The causes of variation in statistical process control are

A(n) __________ is a graph that describes how well an acceptance plan discriminates between good and bad lots.

Operations and Productivity

Operations Strategy in a Global Environment

Project Management

Forecasting

Design of Goods and Services

Managing Quality

Process Strategy

Capacity and Constraint Management

Location Strategies

Layout Strategies

Human Resources, Job Design, and Work Measurement

Supply-Chain Management

Outsourcing as a Supply-Chain Strategy

Inventory Management

Aggregate Planning

Material Requirements Planning MRP and ERP

Short-Term Scheduling

Just-In-Time and Lean Options

Maintenance and Reliability

Decision-Making Tools

Linear Programming

Transportation Models

Waiting-Line Models

Learning Curves

Simulation

Filters

Exam 7: Statistical Process Control

According to the text, the most common choice of limits for control charts is usually

The __________ is a quality control chart used to control the number of defects per unit of output.

A bank's manager has videotaped 20 different teller transactions to observe the number of mistakes being made. Ten transactions had no mistakes, five had one mistake and five had two mistakes. Compute proper control limits at the 90% confidence level.

The purpose of process control is to detect when natural causes of variation are present.

The Central Limit Theorem

The type of inspection that classifies items as being either good or defective is

Which of the following statements on acceptance sampling is true?

An acceptance sampling plan must define "good lots" and "bad lots" and specify the risk level associated with each one.

A p-chart is appropriate to plot the number of typographic errors per page of text.

Which of the following statements about acceptance sampling is true?

A lot that is accepted by acceptance sampling is certified to be free of defects.

The causes of variation in statistical process control are

A(n) __________ is a graph that describes how well an acceptance plan discriminates between good and bad lots.

Operations and Productivity

Operations Strategy in a Global Environment

Project Management

Forecasting

Design of Goods and Services

Managing Quality

Process Strategy

Capacity and Constraint Management

Location Strategies

Layout Strategies

Human Resources, Job Design, and Work Measurement

Supply-Chain Management

Outsourcing as a Supply-Chain Strategy

Inventory Management

Aggregate Planning

Material Requirements Planning MRP and ERP

Short-Term Scheduling

Just-In-Time and Lean Options

Maintenance and Reliability

Decision-Making Tools

Linear Programming

Transportation Models

Waiting-Line Models

Learning Curves

Simulation

Filters