Exam 24: Waiting-Line Models

At the order fulfillment center of a major mail-order firm,customer orders,already packaged for shipment,arrive at the sorting machine to be sorted for loading onto the appropriate truck for the parcel's address.The arrival rate at the sorting machine is at the rate of 100 per hour following a Poisson distribution.The machine sorts at the constant rate of 150 per hour. a.What is the utilization rate of the system? b.What is the average number of packages waiting to be sorted? c.What is the average number of packages in the sorting system? d.How long must the average package wait until it gets sorted? e.What would Lq and Wq be if the service rate were exponential,not constant?

A waiting line meeting the M/M/1 assumptions has an arrival rate of 10 per hour and a service rate of 12 per hour.What is the probability that the waiting line is empty?

Why must the service rate be greater than the arrival rate in a single-channel system?

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

A small hair styling 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

A(n)________ queuing system has one line and one server.

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

Which one of the following is not a characteristic of a Model B or M/M/S 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.

Most banks have changed from having a line in front of each teller to a system where one line feeds all tellers.Which system is better? Why?

Which of the following is not an assumption of the M/M/1 model?

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?

A(n)________ occurs when an arrival refuses to enter a waiting line;a(n)________ occurs when an arrival joins a waiting line,then leaves it.

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

"Women and children first!" declares the captain of a sinking ship.His directive employs which of the following queue disciplines in disembarking passengers?

Waiting-line models are useful to operations in such diverse settings as service systems,maintenance activities,and shop-floor control.

Students arrive randomly at the help desk of the computer lab.There is only one service agent,and the time required for inquiry varies from student to student.Arrival rates have been found to follow the Poisson distribution,and the service times follow the negative exponential distribution.The average arrival rate is 12 students per hour,and the average service rate is 20 students per hour.How many students,on the average,will be waiting in line at any one time?

A queuing model which follows the M/M/1 assumptions has λ = 3 and μ = 2.The average number in the system is

A hospital emergency room always follows a first-in,first-served queue discipline in the interest of fairness.

A(n)________ is a discrete probability distribution that often describes the arrival rate in queuing theory.