While the queueing system observer was able to record the times of arrival of customer to the queue and the time spent while being served, the observer could not clearly see how many bank tellers were working, but suspected it was one or two.

4.5.Would you be able to tell the exact number of tellers? SHOW YOUR WORK!

4.6. What proportion of the time are the tellers idle?

4.7. What is the average time a customer spends in the system?

H23 B D G H 1 Customer No. Inter-arrival time Arrival time Service Time Time service begins Waiting time Time service ends Time in system Idle time of server 2 1 - 0 5 0 0 5 5 0 3 2 1 1 2 5 4 7 6 0 3 5 6 12 7 1 19 13 0 5 4 2 8 18 19 11 37 29 0 6 5 6 14 8 37 23 45 31 0 7 6 4 18 10 45 27 55 37 0 8 7 8 26 9 55 29 38 0 9 8 2 28 7 64 36 71 43 0 10 3 31 32 71 40 103 72 0 11 10 4 35 20 103 68 123 88 0 12 11 1 36 4 123 87 127 91 0 13 12 2 38 2 127 89 129 91 0 14 13 10 48 6 129 81 135 87 0 15 14 12 60 8 135 75 143 83 0 16 15 5 65 14 78 157 92 0 17 16 4 69 12 88 100 0 18 17 3 22 13 169 97 182 110 0 19 18 2 74 5 182 108 187 113 0 20 19 4 78 4 187 109 191 113 0 21 20 3 81 12 191 110 203 122 0 22 Q4.1 Average: 10.15 23 Q4.2 Average: 58.05 24 Q4.3 Average 61.1052632 25 Q4.4 Proportion: 95.00% DOON 143 157 169