In: Operations Management
The Bijou Theater shows vintage movies. Customers arrive at the
theater line at the rate of 80 per hour. The ticket seller averages
36 seconds per customer, which includes placing validation stamps
on customers’ parking lot receipts and punching their frequent
watcher cards. (Because of these added services, many customers
don’t get in until after the feature has started.) (Use the Excel
spreadsheet Queue Models.)
a. What is the average customer time in the
system? (Round your answer to 2 decimal
places.)
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b. What would be the effect on customer time in the system of having a second ticket taker doing nothing but validations and card punching, thereby cutting the average service time to 25 seconds? (Round your answer to 3 decimal places.)
Average time in system ________ minutes
c. What would be the customer time in the system if instead of the change in Part b, a second window was opened with each server doing all three tasks? (Do not round intermediate calculations. Round your answer to 3 decimal places.)
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d. Would system waiting time which is obtained in part (c) be less than you found in (b)?
Yes
No
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This is M/M/1 queue system with following characteristics
Arrival rate, λ = 80 per hour
Service rate, μ = 3600 seconds per hour / 36 seconds per customer = 100 customers per hour
(a) Average customer time in system, W = 1/(μ-λ) = 1/(100-80) = 0.05 hour = 3 minutes
(b) New service rate = 3600/25 = 144
Average time in system = 1/(144-80) = 0.0156 = 0.928 minutes
(c) This becomes M/M/s queue system , with s = 2
Calculation of queue characteristics is done using table in excel as below.
Average time in system = 0.0119 hour = 0.714 minute
Formula: B12 =($B$4/$B$5)^A12/FACT(A12) copy to B13
C13 =SUM(B$11:$B12)
D13 =+B13/(1-$B$4/(A13*$B$5))
E13 =1/(C13+D13)
F13 =$B$4/($B$5*A13)
G13 =+E13*B13*F13/(1-F13)^2
H13 =G13+$B$4/$B$5
I13 =G13/$B$4
J13 =I13+1/$B$5
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