# PQM Final

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Know the objective of maintenance and reliability

to maintain the capability of the system
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Know the definition of reliability

the probability that a machine part or product will function properly for a specified time under stated conditions
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Know different reliability tactics

Improving individual components, providing redundancy
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Know what the MTBF measures

Operating time between failures
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Know the different applications of linear programming

Product mix problem,
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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
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Know what an objective function is

a mathematical expression in linear programming that maximizes or minimizes some quantity (often profit or cost)
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Know what \”feasible solution space\” means

The region which satisfies all of the constraints in graphical linear programming
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Know what the \”corner point solution\” requires

finding the coordinates (profit) at each corner of the feasible solution space
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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
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Ls

average # units in system
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Ws

total time in system
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q

time in the queu (waiting to be served)
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Lq

average # units waiting to be served
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Wq

average time a unit spends waiting in the queue; longer than Lq
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Know what \”poisson\” means

The arrival rate in queuing theory
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In queuing problems, which of the following probability distributions is typically used to describe the number of arrivals per unit of time

Poisson
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Know the characteristics of a waiting line

Waiting time to be served and waiting time in system
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Which of the following is NOT a common queuing situation

parcel delivery truck following its computer-generated route
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Model A

Single Channel; one door; Poisson
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Model B

Multi-channel distribution; more than one door
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Model C

Constant service; single channel; constant arrival and constant service
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An airline ticket counter, with several agents for one line of customers, is an example of

A multi-channel, single phase system
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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)
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The sign at the bank reads \”Wait here for the next available teller\” suggests the use of what waiting line system

Multi Channel
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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
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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
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Which one of the following is NOT a characteristic of a model B

single channel
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Which of the following is NOT a characteristic of a Model A

limited population size
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P=£/µ

percent of time that the machine is used
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Lq=£²[µ(µ-£)]

the average length of the queue
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Ls=£/(µ-£)

the average # of students in the system
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Wq=£/µ(µ-£)

the average time spend waiting in the queue
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Ws=1/µ-£

average time in the system
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£/µ