moduleDsolutions

moduleDsolutions - MODULE D DISCUSSION QUESTIONS 2. The...

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MODULE D DISCUSSION QUESTIONS 2. The assumptions underlying the standard waiting line or queuing model are: n Arrivals are served on a “first come, first served” (FCFS, or FIFO) basis; and every arrival waits to be served regardless of the length of the line or queue. n All arrivals are independent of preceding arrivals, and the average number of arrivals per unit time (arrival rate) does not change over time. n Arrival rates are described by a Poisson probability distribution, and arrivals come from an infinite or very large source. n Service times vary from one customer to another and are independent of one another, but their average rate is known. n Service times are described by a negative exponential probability distribution. n The effective service rate is faster than the arrival rate. 4. If the service rate is not greater than the arrival rate, the line will increase in length indefinitely. 12. This deals with the interesting issue of the value of waiting time. Some service organizations place a very low value on your time, leading to a good classroom discussion. 15. Supermarkets simply do not have enough space to set up a common line, so they use a separate queue for each checkout station. 16. The cost trade-offs in queuing are waiting cost versus service cost. END-OF-MODULE PROBLEMS D.1 (a) ρ λ μ = = = 40 60 2 3 (b) L q = - ( 29 = - = ( 29 ( 29 μμ 2 2 40 60 60 40 4 3 (c) L s = - = - = 40 60 40 2 (d) W q = - ( 29 = - = = ( 29 40 60 60 40 0 033 2 . hours minutes (e) W s = - = - = = 1 1 60 40 1 20 3 hour minutes = 40/hour, = 60 /hour D.2 (a) = = = 40 90 0 44 44% . (b) L q = - = ( 29 ( 29 40 90 90 40 0 356 2 . (c) L s = - = 40 90 40 0 8 . (d) W q = - = = = ( 29 40 90 90 40 0 0089 0 533 . . hours minutes 32 seconds (e) W s = - = = = 1 90 40 1 50 12 hour minutes 72 seconds .
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This note was uploaded on 02/15/2012 for the course BA 252 taught by Professor Jamescampbell during the Winter '03 term at UMSL.

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moduleDsolutions - MODULE D DISCUSSION QUESTIONS 2. The...

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