Sample test

# Sample test - PRACTICE EXAM 1 Which of the following...

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PRACTICE EXAM 1. Which of the following statements concerning waiting line cost analysis is true? a) there is a positive relationship between service cost and the cost of waiting b) the cost of waiting is direct and relatively easy to compute, while the cost of service is more difficult to derive c) as capacity is added waiting time goes up d) waiting costs include the loss of productive time due to employees waiting for services (Answer: d) {Statement (a) is false. There is an inverse relationship between the cost of service (which increases as capacity increases) and the cost of waiting (which decreases as capacity increases). This is illustrated in Figure 16.3 in the text. Statement (b) is also false. In fact the cost of providing service is often very straightforward since that cost is usually the wages of an additional person or the operating costs of an additional machine. The costs of waiting are much more nebulous and difficult to measure since they involve things like customer good will and potential loss of future business. Statement (c) is also false. As capacity is added to the system the waiting times, and therefore the waiting costs, decline. Statement (d) is true in that sometimes the costs of waiting can be measured by the loss of productive time and the wages paid for our own employees waiting for tools, copy machine, or other services. In these cases the costs of waiting are more easily computed.} 2. In a particular waiting line problem, the mean arrival rate is 7 per hour. The average service rate for an individual server is 3 per hour. In order for the system to function properly, i.e., not build an infinite queue, what is the minimum number of servers required? a) 3 servers b) 1 server c) 2 servers d) any number of servers will function properly (Answer: a) {Text on page 725: In any queuing system the effective service rate must be greater than the arrival rate or the queue will continue to build. In the single server case this means that λ > μ . In the multiple server case, s μ is the effective service rate and must be larger than λ . In this case that means that 3s must be larger than 7 or s must be at least 3.} 3. As the variability of the service times is reduced

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a) the average waiting time increases b) the utilization factor increases c) more capacity is required to provide the same service coverage d) the average waiting time decreases (Answer: d) {Text on page 733: As can be seen from the equations for the length of the queue in the constant service time case, the length of the queue is one half that in the basic single server case. All other statistics will therefore also improve. In other words, as the variability of the services times decreases, the average
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Sample test - PRACTICE EXAM 1 Which of the following...

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