14 Waiting Line Models MULTIPLE CHOICE 1. Decision makers in queuing situations attempt to balance a. operating characteristics against the arrival rate. b. service levels against service cost. c. the number of units in the system against the time in the system. d. the service rate against the arrival rate. ANSWER: b TOPIC: Introduction 2. Performance measures dealing with the number of units in line and the time spent waiting are called a. queuing facts. b. performance queues. c. system measures. d. operating characteristics. ANSWER: d TOPIC: Introduction 3. If arrivals occur according to the Poisson distribution every 20 minutes, then which is NOT true? a. λ = 20 arrivals per hour b. λ = 3 arrivals per hour c. λ = 1/20 arrivals per minute d. λ = 72 arrivals per day ANSWER: a TOPIC: Distribution of arrivals 4. The manner in which units receive their service, such as FCFS, is the a. queue discipline. b. channel. c. steady state. d. operating characteristic. ANSWER: a TOPIC: Queue discipline 1 This edition is intended for use outside of the U.S. only, with content that may be different from the U.S. Edition. This may not be resold, copied, or distributed without the prior consent of the publisher.
2 Chapter 14 Waiting Line Models 5. In a waiting line situation, arrivals occur, on average, every 10 minutes, and 10 units can be received every hour. What are λ and μ ? a. λ = 10, μ = 10 b. λ = 6, μ = 6 c. λ = 6, μ = 10 d. λ = 10, μ = 6 ANSWER: c TOPIC: Structure of a waiting line system 6. Operating characteristics formulas for the single-channel queue do NOT require a. λ > μ . b. Poisson distribution of arrivals. c. an exponential distribution of service times. d. an FCFS queue discipline. ANSWER: a TOPIC: Operating characteristics 7. In a multiple channel system a. each server has its own queue. b. each server has the same service rate. c. μ . > λ d. All of the alternatives are correct. ANSWER: b TOPIC: Multiple channel waiting line 8. Little's flow equations a. require Poisson and exponential assumptions. b. are applicable to any waiting line model. c. require independent calculation of W, L, W q , and L q . d. All of the alternatives are correct. ANSWER: b TOPIC: General relationships for waiting line models 9. The total cost for a waiting line does NOT specifically depend on a. the cost of waiting. b. the cost of service. c. the number of units in the system. d. the cost of a lost customer. ANSWER: d TOPIC: Economic analysis 10. Models with a finite calling population a. have an arrival rate independent of the number of units in the system. b. have a service rate dependent on the number of units in the system. c. use the size of the population as a parameter in the operating characteristics formulas. d.
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