Exam 15: Waiting Line Models

Explain what is meant by the following statement,"operating characteristics are non-optimizing."

The equations provided in the textbook for computing operating characteristics apply to a waiting line operating

With no waiting allowed,operating characteristics L_q and W_q are automatically zero regardless of the number of servers.

How can a system be changed to improve the service rate?

For all waiting lines,P₀ + P_w = 1.

For an M/M/1 queuing system,if the service rate,µ,is doubled,the average wait in the system,W,is cut in half.

Andy Archer,Ph.D.,is a training consultant for six mid-sized manufacturing firms.On the average,each of his six clients calls him for consulting assistance once every 25 days.Andy typically spends an average of five days at the client's firm during each consultation. Assuming that the time between client calls follows an exponential distribution,determine the following: a.the average number of clients Andy has on backlog b.the average time a client must wait before Andy arrives to it c.the proportion of the time Andy is busy

The 8 students in a seminar class must come to the professor's office to turn in a paper and give a 5-minute oral summary.Assume there is a service rate of 10 per hour and adequate time is available for all.The arrival rate for each unit is 5 per hour.What is the probability there is no one in the office or waiting when you come?

Two new checkout scanning systems are under consideration by a retail store.Arrivals to the checkout stand follow the Poisson distribution with  = 2 per minute.The cost for waiting is $18 per hour.The first system has an exponential service rate of 5 per minute and costs $10 per hour to operate.The second system has an exponential service rate of 8 per minute and costs $20 per hour to operate.Which system should be chosen?

The total cost for a waiting line does not specifically depend on

For a single-channel waiting line,the utilization factor is the probability that an arriving unit must wait for service.

If some maximum number of customers is allowed in a queuing system at one time,the system has a finite calling population.

The manner in which units receive their service,such as FCFS,is the

Models with a finite calling population

If arrivals occur according to the Poisson distribution every 20 minutes,then which is not true?

For an M/M/k system,the average number of customers in the system equals the customer arrival rate times the average time a customer spends waiting in the system.

If service time follows an exponential probability distribution,approximately 63% of the service times are less than the mean service time.

The assumption of exponentially distributed service times indicates that

Queue discipline refers to the manner in which waiting units are arranged for service.

Queue discipline refers to the assumption that a customer has the patience to remain in a slow moving queue.