Concept explainers
a)
To model: The system as M/M/1 queue.
Introduction: In order to predict the waiting time and length of the queue, queueing model will be framed. Queueing theory is the mathematical model that can be used for the decision-making process regarding the resources required to provide a service.
b)
To determine: The average number of taxis that are waiting for the customers.
Introduction: In order to predict the waiting time and length of the queue, queueing model will be framed. Queueing theory is the mathematical model that can be used for the decision-making process regarding the resources required to provide a service.
c)
To determine: The revenue will the taxis receive.
Introduction: In order to predict the waiting time and length of the queue, queueing model will be framed. Queueing theory is the mathematical model that can be used for the decision-making process regarding the resources required to provide a service.
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Chapter 12 Solutions
Practical Management Science
- During nearly four decades of business operations, Memphis-based FedEx has earned a reputation for reliable, on-time delivery of packages to homes and offices around the country. Founder Fred Smith originally focused on overnight deliveries, choosing Memphis as the company’s headquarters because the airport rarely closes due to bad weather. With FedEx’s planes departing and arriving on schedule nearly all the time, its express shipments usually remained on schedule, then and now. To reassure customers that delivery will take place when and where promised, the firm offers a money-back guarantee on time-sensitive express shipments, among other services. FedEx has steadily expanded its portfolio of services since the 1970s. Its original overnight express delivery is currently available to U.S. customers in various forms, including “first-overnight” delivery, next-morning delivery, next-afternoon delivery, and budget-pleasing two- or three-day delivery. The company’s services also include cost-effective ground delivery for parcels and extra-speedy same-day delivery for urgent deliveries within 1,800 cities. Over the years, FedEx has widened its delivery network to more than 220 countries. It has purchased more cargo jets and acquired specialized shipping firms, including Tiger International, Roberts Express, RPS, and TNT Express, to support global growth. For international business customers needing products, parts, or raw materials shipped across countries or continents, the company now offers time-saving services such as commercial freight forwarding and cross-border logistical support. To add the convenience of local drop-off and pickup points for U.S. consumers and small businesses, FedEx acquired the Kinko’s office services company in 2004 and later rebranded it as FedEx Office. This acquisition also added printing and copying to the menu of services offered. Then the company arranged for large U.S. retailers such as Walgreens, Albertsons, Kroger, and Safeway to accept packages for shipment and receive package delivery for customer pickup in thousands of store locations. This means people who want to send a package can head to a nearby retailer and ship where they shop, rather than making a separate trip to the FedEx location. It’s also a safe alternative for packages to be picked up by people who don’t want FedEx shipments left by the front door. Another service FedEx offers to small and mid-sized businesses, including retailers, is FedEx Fulfillment. The purpose is to expedite order fulfillment by having each business store its products in a FedEx warehouse. Then, when the business’s customers place orders, FedEx puts the products into boxes bearing the business’s own logo and ships directly to those customers. The business doesn’t need a separate warehouse or staff for fulfillment, and packages are on their way to customers more quickly because the products were in FedEx’s warehouse, ready to be packed and shipped. This service puts FedEx into direct competition with Amazon.com, which offers a similar service to merchants that sell through the online Amazon Marketplace. But it also gives businesses that don’t sell via Amazon a fast and professional fulfillment alternative. FedEx is careful to let customers know, through media and social-media announcements, when it anticipates that extreme weather or other conditions will cause delays or force it to halt pickups and deliveries. For the duration of Hurricane Irma, for example, FedEx said it would suspend deliveries in Florida. Some Florida customers who had ordered generators to be delivered via FedEx were unhappy, because they worried about being without power during and after the storm. But one FedEx employee loaded several generator orders into his car and took them to customers himself. When a customer posted a grateful compliment to FedEx on Facebook, the message generated thousands of likes, shares, and positive comments. The company also received positive comments for its donations of cash and transportation services to areas devastated by Hurricanes Irma, Harvey, and Maria. According to the American Customer Satisfaction Index (ACSI), FedEx often tops the list of U.S. shipping companies as ranked by customers surveyed. Every day, the company delivers 13 million packages—and during the busy year-end holiday season, it delivers many more. By meeting customers’ expectations for on-time deliveries, FedEx has increased annual revenues beyond $60 billion and positioned itself for continued growth in the future. How does FedEx’s money-back guarantee address customers’ concerns about heterogeneity?arrow_forwardNote: Formulas to solve the following problems are given in the class and example problems were solved in the class. Follow the examples described in the class and read the literature posted on blackboard. 1. Huntsville Bank (a fictitious one) has a drive-through teller window and observed that customers arrive for service one every three minute, on an average, and the average service time per customer is 2.4 minutes. Assume inter-arrival time and service time follow a negative Exponential distribution. The bank hires you as a consultant. You guess that this is an M|M|1 system and you are required to determine the following: a. Probability (teller is busy) b. Probability (teller is idle) c. Average number of customers waiting for service, that is, number of autos in the line excluding the one at the teller window. d. Average number of customers in the system, that is, number of autos in the line including the one at the teller window. e. Average time a customer spends in the waiting…arrow_forwardIn an M/M/1 queueing system, the arrival rate is 5 customers per hour and the service rate is 7 customers per hour. What is the expected number of customers in the system (L)? (Round your answer to 3 decimal places.) What is the expected waiting time in the system (W)? (Express the waiting time in hours, round your answer to 3 decimal places.) What is the expected number of customers in the queue(Lq)? (Round your answer to 3 decimal places.) What is the expected waiting time in the queue(Wq)? (Express the waiting time in hours, round your answer to 3 decimal places.)arrow_forward
- please do not copy other's work,thank you very mucharrow_forwardCustomers arrive at a server queuing system according to a Poisson process with mean rate of 30 per hour. If the server works continuously, the number of customers it can serve in an hour has Poisson distribution with mean 50. } Determine the proportion of the time during which no one waits for service.arrow_forward3 The M/M/1 Queue During peak time, customers arrive at a bank teller window (with a single teller) at a rate of 23 per hour, where the teller can serve 25 per hour. This problem will allow you to investigate (via a simple extension of the mean queue size formula) the effect of highly-variable service times on our familiar queuing metrics. The diagram below stylizes the queuing system: Waiting Service Calculate the marginal probability P (T > oT). a. O b. 0.25 O c. 0.63 O d. 0.75 Calculate the mean time a customer spends at the bank (waiting time plus service time) in minutes. O a. 30 minutes O b. 27.6 minutes O c. 2.4 minutes O d. 7 minutesarrow_forward
- In an M/M/1 queueing system, the arrival rate is 7 customers per hour and the service rate is 12 customers per hour. (Round your answers to 3 decimal places) a. What is the probability that the server will be idle? b. What is the probability of having exactly 4 customers in the system? c. What is the probability of having 4 or fewer customers in the system?arrow_forwardThe Peachtree Airport in Atlanta serves light aircraft. It hasa single runway and one air traffic controller to landplanes. It takes an airplane 8 minutes to land and clear therunway (exponentially distributed). Planes arrive at theairport at the rate of 5 per hour (Poisson distributed).a. Determine the average number of planes that will stackup waiting to land.b. Find the average time a plane must wait in line before itcan land.c. Calculate the average time it takes a plane to clear therunway once it has notified the airport that it is in thevicinity and wants to land.d. The FAA has a rule that an air traffic controller can, onthe average, land planes a maximum of 45 minutes outof every hour. There must be 15 minutes of idle timeavailable to relieve the tension. Will this airport have tohire an extra air traffic controller?arrow_forwardMany banks and post offices have switched from having a line at each teller or clerk to a single waiting line cordoned off by a set of ropes or chains. Examine this change by considering the following two cases: A. Case 1. Customers arrive at a bank at an average rate of 80 per hour and form a single line. There are five tellers, and the average service time is 3.0 minutes for each teller. Assuming exponential interarrival and service times, how long is the average wait in line? B. Case 2. Customers arrive at a teller's window at a rate of 16 per hour. There are five tellers so that the total arrival rate is 80 per hour. There is separate line at each window (with no switching between lines). As in Case 1, the average service time for each teller is 3.0 minutes. How long is the average wait in line? C. Comment on the results of Cases 1 and 2. What additional factors might affect waiting times in a real banking situation?arrow_forward
- The Minute Stop Market has one pump for gasoline, which can service 10 customers per hour (Poisson distrib-uted). Cars arrive at the pump at a rate of 5 per hour (Poisson distributed). a. Determine the average queue length, the average time acar is in the system, and the average time a car must wait.b. If, during the period from 4:00 P.M. to 5:00 P.M., thearrival rate increases to 12 cars per hour, what will bethe effect on the average queue length?arrow_forwardConsider a Poisson queue with random arrivals at the rate of 12 customers per hour and the following steady- state probabilities: po = 1/3, p1 = 1/2, p2 = 1/6, and p, = 0 for n = 3,4,5, ... . What is the mean (or effective) arrival rate in customers per hour for this queuing system? Consider drawing a rate diagram to assist in your solution. O 10 12 O none of the other choices O 2arrow_forwardMany of a bank’s customers use its automatic teller machine to transact business after normal banking hours. During the early evening hours in the summer months, customers arrive at a certain location at the rate of one every other minute. This can be modeled using a Poisson distribution. Each customer spends an average of 94 seconds completing his or her transactions. Transaction time is exponentially distributed. a. Determine the average time customers spend at the machine, including waiting in line and completing transactions. (Do not round intermediate calculations. Round your answer to the nearest whole number.) Average time minutes b. Determine the probability that a customer will not have to wait upon arriving at the automatic teller machine. (Round your answer to 2 decimal places.) Probability c. Determine the average number of customers waiting to use the machine. (Round your answer to 2 decimal places.) Average number customersarrow_forward
- Practical Management ScienceOperations ManagementISBN:9781337406659Author:WINSTON, Wayne L.Publisher:Cengage,MarketingMarketingISBN:9780357033791Author:Pride, William MPublisher:South Western Educational Publishing