BU275 Lecture Notes - Lecture 14: Queueing Systems, Photocopier
Document Summary
Recall our m/m/1 queueing system, with arrival rate and service rate (inter-arrival times and service times and service times are exponential) But, the service time is 15 seconds=1/ , so the service rate =4 customers/minute. Recall our m/m/1 formulas for average # of people in system: l= /( - )=3/(4-3)=3 customers. Average time in system: w=1/( - )=1/(4-3)=1 minute, (remember these are only m/m/1 formulas) Little"s law: applies to most (all?) queues, l= w, people in system=arrival rate time in system, also. Suppose: =3 customers/min, =4 customers/minute, wq=45 seconds, even if this is not an m/m/1 queue, Aside: little"s law explained: you arrive at the store expecting to spend 1 minute in the store. How many people are in front of you (each with service time 15 sec) Those are probably 3 people in front of you: by the time you leave the store, 1 minute has passed. Average of 3 people in the store.
