Ch 13

Question 1

Whose notation for queues is a popular classification system for identifying features of a queue

Answer 1

Kendall’s Notation for Queues

Question 2

Which notation for queues involves shorthand notation where A/B/C/D/E describe the queue and are applicable to a large number of queuing scenarios

Answer 2

Kendall’s Notation for Queues

Question 3

What does A stand for in Kendall’s notation for queues

Answer 3

Inter-arrrival time distribution (poisson)

Question 4

What does B stand for in Kendall’s notation for queues

Answer 4

Service time distribution (exponential)

Question 5

What does C stand for in Kendall’s notation for queues

Answer 5

Number of parallel servers

Question 6

What does D stand for in Kendall’s notation for queues

Answer 6

Maximum numbers of jobs that can be in the system (waiting and in service) - default is infinite for infinite number of waiting positions

Question 7

What does E stand for in Kendall’s notation for queues

Answer 7

Queuing disciplines (FCS,LCFS,PR, etc)- default is FCFS/FIFO

Question 8

For A and B of Kendall’s Notation for Queues , distributions may be notated as>

Answer 8

“M”: poisson/expnential
D: deterministic
E_k: Erlangian (order k)
G: General

Question 9

Which term is defined as a body of knowledge about waiting lines and is valuable tool for service ops managers as they must recognize the
tradeoff between cost of providing good service and cost of customer waiting time

Answer 9

Queuing Theory

Question 10

What are the key points of the queuing thoery

Answer 10

• Want short queues so customers do not leave
  -Willing to allow some waiting if it is balanced by a significant
  savings in capacity costs

Question 11

Which basic queuing system configuration is the most simple queue configuration that uses the poisson distribution for arrivals, exponential distribution for service time with 1 single server

Answer 11

M/M/1

Question 12

Which basic queuing system configuration channel refers to the number of servers. The phase refers to the number of stops or stations that must be made by the customer to complete the service. An example of this queue is a drive thru bank with only one lane

Answer 12

Single channel, single phase

Question 13

Which basic queuing system configuration can be described below:
A restaurant where you place your order at step 1 and you pay for your order at step 2 is an example for what?

Answer 13

Single channel, multi phase

Question 14

Which basic queuing system configuration can be described below:
a single line at a store with multiple cashiers,
i.e. Dick’s Sporting Goods or Wendy’s

Answer 14

Multi Channel, single phase

Question 15

Which basic queuing system configuration can be described below:
Example: a laundromat where you have a choice between two washing
machines to first wash your clothes and a choice between 2 dryers to dry
your clothes after they’ve completed the wash step

Answer 15

Multi channel, multi phase

Question 16

What law was created and proved by John Little and states “the average number of customers in a system
(L) is equal to the arrival rate (λ) times the average waiting time (W)”

Answer 16

Little’s Law

Question 17

Why is Little’s Law important for ALL businesses?

Answer 17

-It is applied to calculate the capacity of systems
* In a manufacturing setting we view the variables a little differently
− L = work in progress (WIP) instead of customer volume
− λ = Throughput (departure rate or production output) instead of customer’s
arrival rate
− W = Lead time (the time an item spends in a system) instead of people spend
waiting at a business
− So L=λW becomes…
WIP = Throughput x Lead Time