2 - Queuing Theory Flashcards

1
Q

What is the cost of waiting?

A

Opportunity cost for customers
Cost of building space for queues

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2
Q

What are the benefits of waiting? (3)

A

Product might be better
May be good marketing
Can lead to more profit

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3
Q

Can you store capacity?

A

No

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4
Q

Ways to reduce waiting times from the demand side? (4)

A

1- Appointment/reservation
2- EZ pass
3- Flash pass
4- Global entry/nexus

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5
Q

Ways to reduce waiting times from the supply side? (2)

A

1-Flexible server
2- Triage (hospital)

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6
Q

Ways to reduce waiting times from both side (2)

A

1- Surge Pricing (Uber)
2- Self-checkout

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7
Q

What is the decision problem?

A

We have to balance capacity cost with waiting cost

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8
Q

What is μ

A

μ : average service rate

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9
Q

What is 1/μ

A

1/μ : Average service time

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10
Q

What is lambda

A

lambda: Average arrival rate

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11
Q

In an M/M/1 system, what is the equation for the average number of units in the system

A

Ls = lambda / (µ l lambda)

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12
Q

In an M/M/1 system, what is the equation for the average time in system

A

Ws = 1 / (µ l lambda)

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13
Q

In an M/M/1 system, what is the equation for the average number of units in the queue

A

Lq = (lambda)^2 / µ (µ - lambda)

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14
Q

In an M/M/1 system, what is the equation for the average time in queue?

A

Wq = lambda / µ (µ - lambda)

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15
Q

In an M/M/1 system, what is the equation for the system utilization

A

p = lambda / μ

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16
Q

In an M/M/s system, what is the equation for the average number of units in queue

A

Check from the table

17
Q

In an M/M/s system, what is the equation for the average time in queue

A

Wq = Lq / lambda

18
Q

In an M/M/s system, what is the equation for the average number of units in the system

A

Ls = lambda * Ws

19
Q

In an M/M/s system, what is the equation for the average time in the system

A

Ws = Ls / lambda

20
Q

In an M/M/s system, what is the equation for the system utilization?

A

p = lambda / sµ

21
Q

In an M/M/s system, what is the equation for the average service time

A

1/µ = Ws - Wq

22
Q

when in a system with multiple single-queue, what is lambda

A

lambda = lambda/s

23
Q

What are the 2 observations between a common queue system and a multiple single-queues system?

A
  1. Utilization is the same
  2. Lower waiting time in the common queue