Exam 20: Waiting-Line Models

The shopper who says to himself, "I've waited too long in this line. I don't really need to buy this product today," and leaves the store is an illustration of which element of arrival behavior?

Suppose that, on average, 4 customers arrive each minute in a Poisson distribution. P(x) is the probability of x arrivals. Which of the following is TRUE?

An airline ticket counter, with several agents for one line of customers, is an example of which of the following?

In the basic queuing model (M/M/1), what probability distribution describes arrival rates?

A manufacturing plant is trying to determine how long the average line for a repair process will be. If 10 machines arrive each hour and must wait 6 minutes in the line, how long will the line be, on average?

The potential restaurant customer who says to her husband, "The line looks too long; let's eat somewhere else," is an illustration of which element of arrival behavior?

Balk and renege are elements of queue discipline.

The greater the margin by which the arrival rate exceeds the service rate, the better the performance of the waiting line.

A crew of mechanics at the Highway Department Garage repair vehicles that break down at an average of λ = 7.5 vehicles per day (approximately Poisson in nature). The mechanic crew can service an average of μ = 12 vehicles per day with a repair time distribution that approximates a negative exponential distribution. (a) What is the utilization rate for this service system? (b) What is the average time before the facility can return a breakdown to service? (c) How much of that time is spent waiting for service? (d) How many vehicles are likely to be in the system at any one time?

A system in which the customer receives service from only one station and then exits the system is which of the following?

A queuing model that follows the M/M/1 assumptions has λ = 10 and μ = 15. What is the average number of units in the system?

A waiting line meeting the M/M/1 assumptions has an arrival rate of 4 per hour and a service rate of 10 per hour. What is the probability that the waiting line is empty?

Little's Law is NOT applicable in which of the following situations?

Four of the most widely used waiting line models-M/M/1 or A, M/M/S or B, M/D/1 or C, and Finite population or D-all share which of the following three characteristics?

A waiting line or ________ is where items or people are in a line awaiting service; ________ is a body of knowledge about waiting lines.

Provide an example of a limited or finite population for a queue.

Which one of the following is NOT a characteristic of a Model C or M/D/1 system?

A(n) ________ queuing system has one waiting line, but several servers; a(n) ________ queuing system is one in which the customer receives services from several stations before exiting the system

A waiting-line system that meets the assumptions of M/M/1 has λ = 1, μ = 4. For this system, what is the probability of less than two units in the system?

LIFS (last-in, first-served) is a common queue discipline, most often seen where people, not objects, form the waiting line.