# PQM Final

Know the objective of maintenance and reliability
to maintain the capability of the system
Know the definition of reliability
the probability that a machine part or product will function properly for a specified time under stated conditions
Know different reliability tactics
Improving individual components, providing redundancy
Know what the MTBF measures
Operating time between failures
Know the different applications of linear programming
Product mix problem,
Which of the following is NOT a requirement of a linear programming problem
for each decision variable there must be one constraint or resource limit
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Know how a constraint would be written in linear programming
2X + 7Y ≥ 100
Know what an objective function is
a mathematical expression in linear programming that maximizes or minimizes some quantity (often profit or cost)
Know what “feasible solution space” means
The region which satisfies all of the constraints in graphical linear programming
Know what the “corner point solution” requires
finding the coordinates (profit) at each corner of the feasible solution space
Study of waiting-line models helps operations managers better understand
All of the above…Service systems (bank teller, amusement park rides), repair broken machinery, shop-floor control activities
Ls
average # units in system
Ws
total time in system
q
time in the queu (waiting to be served)
Lq
average # units waiting to be served
Wq
average time a unit spends waiting in the queue; longer than Lq
Know what “poisson” means
The arrival rate in queuing theory
In queuing problems, which of the following probability distributions is typically used to describe the number of arrivals per unit of time
Poisson
Know the characteristics of a waiting line
Waiting time to be served and waiting time in system
Which of the following is NOT a common queuing situation
parcel delivery truck following its computer-generated route
Model A
Single Channel; one door; Poisson
Model B
Multi-channel distribution; more than one door
Model C
Constant service; single channel; constant arrival and constant service
An airline ticket counter, with several agents for one line of customers, is an example of
A multi-channel, single phase system
Understand the variables used to measure a que’s performance
All of the above (utilization factor, average queue length, probability of a specific number of customers, avg waiting time in the line)
The sign at the bank reads “Wait here for the next available teller” suggests the use of what waiting line system
Multi Channel
A small hair salon has several operators. While customers do not have appointments, each is waiting to be served by a specific operator. This scenario provides an example of a
multiple single-channel system, limited queue length
A large discount store and supermarket has a hair salon on its premises. Salon customers can shop in other parts of the store until their name is called for salon service. This scenario provides an example of a
multi-channel, unlimited queue length
Which one of the following is NOT a characteristic of a model B
single channel
Which of the following is NOT a characteristic of a Model A
limited population size
P=£/µ
percent of time that the machine is used
Lq=£²[µ(µ-£)]
the average length of the queue
Ls=£/(µ-£)
the average # of students in the system
Wq=£/µ(µ-£)
the average time spend waiting in the queue
Ws=1/µ-£
average time in the system
£/µ
equals busy
1-£/µ
equals idle