COB 300 OPERATIONS CHAPTER 7
EXAM QUESTIONS WITH COMPLETE
ANSWERS
lower control limit (LCL) for x-bar chart - Answer-x-bar-bar - z(standard deviation of x-
bar)
standard deviation of x-bar - Answer-process standard deviation/square root(sample
size)
range control chart - Answer-control chart used to monitor process dispersion
upper control limit (UCL) for R-chart - Answer-D4(R-bar)
lower control limit (LCL) for R-chart - Answer-D3(R-bar)
p-chart - Answer-control chart for attributes, used to monitor the proportion of defective
items in a process
standard deviation, p - Answer-square root of (p(1-p))/n; used if p is known; if p is
unknown, you replace p with p-bar and standard deviation, p becomes standard
deviation-hat, p
upper control limit (UCL) for p - Answer-p + z(standard deviation, p)
lower control limit (LCL) for p - Answer-p - z(standard deviation, p)
c-chart - Answer-control chart for attributes, used to monitor the number of defects per
unit
upper control limit (UCL) for c - Answer-c + z(square root of c)
lower control limit (LCL) for c - Answer-c - z(square root of c)
If c is unknown...? - Answer-sample estimate, c-bar, is used in place of c
c-bar - Answer-number of defects/number of samples
run test - Answer-test for patterns in a sequence; enables analysts to do a better job of
detecting abnormalities in a process and provides insights into correcting process that is
out of control
run - Answer-sequence of observations with a certain characteristic
, specifications - Answer-range of acceptable values established by engineering design
or customer requirements
process variability - Answer-natural or inherent variability in a process; measured in
terms of process standard deviation
process capability - Answer-inherent variability of process output relative to variation
allowed by the design specification
capability index - Answer-used to assess the ability of a process to meet specifications;
to be deemed capable this must be of at least 1.00 though this means the process is
barely capable; want to aim for at least 1.33
process capability index, Cp - Answer-Specification width/process width OR (upper
specification - lower specification)/6sigma
process capability, Cpk - Answer-used if process is not centered; (upper specification -
process mean)/3sigma AND (process mean - lower specification)/3sigma
reliability - Answer-ability of a product, service, part, or system to perform its intended
function under a prescribed set of conditions; is a probability
independent events - Answer-events whose occurrence or nonoccurence does not
influence each other
probability rules - Answer-Rule 1: If two or more events are independent and success is
defined as the probability that all of the events occur, then the probability of success is
equal
Rule 2: If two events are independent and success is defined as the probability that at
least one of the events will occur, the probability of success is equal to the probability of
either one plus 1.00 minus that probability multiplied by the other probability
Rule 3: If two or more events are involved and success is defined as the probability that
at least one of them occurs, the probability of success is 1-P (all fail)
redundancy - Answer-the use of backup components to increase reliability
mean time between failures (MTBF) - Answer-the average length of time between
failures of a product or component
Quality - Answer-ability of a product to consistently meet or exceed expectations
dimensions of product quality - Answer-performance, aesthetics, special features,
conformance, reliability, durability, perceived quality, servicability
dimensions of service quality - Answer-reliability, responsiveness, time, assurance,
courtesy, tangibles, consistency
EXAM QUESTIONS WITH COMPLETE
ANSWERS
lower control limit (LCL) for x-bar chart - Answer-x-bar-bar - z(standard deviation of x-
bar)
standard deviation of x-bar - Answer-process standard deviation/square root(sample
size)
range control chart - Answer-control chart used to monitor process dispersion
upper control limit (UCL) for R-chart - Answer-D4(R-bar)
lower control limit (LCL) for R-chart - Answer-D3(R-bar)
p-chart - Answer-control chart for attributes, used to monitor the proportion of defective
items in a process
standard deviation, p - Answer-square root of (p(1-p))/n; used if p is known; if p is
unknown, you replace p with p-bar and standard deviation, p becomes standard
deviation-hat, p
upper control limit (UCL) for p - Answer-p + z(standard deviation, p)
lower control limit (LCL) for p - Answer-p - z(standard deviation, p)
c-chart - Answer-control chart for attributes, used to monitor the number of defects per
unit
upper control limit (UCL) for c - Answer-c + z(square root of c)
lower control limit (LCL) for c - Answer-c - z(square root of c)
If c is unknown...? - Answer-sample estimate, c-bar, is used in place of c
c-bar - Answer-number of defects/number of samples
run test - Answer-test for patterns in a sequence; enables analysts to do a better job of
detecting abnormalities in a process and provides insights into correcting process that is
out of control
run - Answer-sequence of observations with a certain characteristic
, specifications - Answer-range of acceptable values established by engineering design
or customer requirements
process variability - Answer-natural or inherent variability in a process; measured in
terms of process standard deviation
process capability - Answer-inherent variability of process output relative to variation
allowed by the design specification
capability index - Answer-used to assess the ability of a process to meet specifications;
to be deemed capable this must be of at least 1.00 though this means the process is
barely capable; want to aim for at least 1.33
process capability index, Cp - Answer-Specification width/process width OR (upper
specification - lower specification)/6sigma
process capability, Cpk - Answer-used if process is not centered; (upper specification -
process mean)/3sigma AND (process mean - lower specification)/3sigma
reliability - Answer-ability of a product, service, part, or system to perform its intended
function under a prescribed set of conditions; is a probability
independent events - Answer-events whose occurrence or nonoccurence does not
influence each other
probability rules - Answer-Rule 1: If two or more events are independent and success is
defined as the probability that all of the events occur, then the probability of success is
equal
Rule 2: If two events are independent and success is defined as the probability that at
least one of the events will occur, the probability of success is equal to the probability of
either one plus 1.00 minus that probability multiplied by the other probability
Rule 3: If two or more events are involved and success is defined as the probability that
at least one of them occurs, the probability of success is 1-P (all fail)
redundancy - Answer-the use of backup components to increase reliability
mean time between failures (MTBF) - Answer-the average length of time between
failures of a product or component
Quality - Answer-ability of a product to consistently meet or exceed expectations
dimensions of product quality - Answer-performance, aesthetics, special features,
conformance, reliability, durability, perceived quality, servicability
dimensions of service quality - Answer-reliability, responsiveness, time, assurance,
courtesy, tangibles, consistency
