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SOLUTIONS MANUAL for Stochastic Modeling: Analysis and ...

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We have assumed a 24-hour day, but perhaps a 12 or 18-hour day is better.<br />

1/µ =2.5 minutessoµ =0.4 calls/minute.<br />

If we treat the connect times as exponentially distributed, then we have an M/M/s/s<br />

queue, where s is the number of ports.<br />

A worthwhile table is π s vs. s, sinceπ s is the probability a user cannot connect.<br />

π s<br />

s<br />

5 0.63<br />

6 0.56<br />

7 0.49<br />

8 0.43<br />

9 0.37<br />

10 0.31<br />

11 0.25<br />

12 0.20<br />

13 0.16<br />

14 0.12<br />

15 0.09<br />

16 0.06<br />

17 0.04<br />

18 0.03<br />

19 0.02<br />

20 0.01<br />

10. (a) If we model the arrival of calls as Poisson, service times as exponentially distributed,<br />

<strong>and</strong> no reneging, then we have an M/M/2 queue.<br />

λ = 20 calls/hour<br />

1/µ =3minutessoµ = 20 calls/hour<br />

(b) To keep up ρ = λ < 1orλ

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