The management of Scotia bank are concerned over a loss of customers at its Georgetown branch. One proposed solution calls for adding one or more drive-thru teller stations so that customers can get quick service without parking. Director of operations David Pentico thinks the bank should risk only the cost of installing one drive-thru. He is informed by his staff that the cost (amortized over a 20-year period) of building a drive-thru is $12 000 per year. It also costs $16 000 per year in wages and benefits to staff each new teller window.

The director of management analysis, Marilyn Hart, believes that the following two factors encourage the immediate construction of two drive-thru stations. According to a recent article in Banking Research magazine, customers who wait in long lines for drive-thru teller service will cost banks an average of $1 per minute in lost goodwill. Also, although adding a second drive-thru will cost an additional $16 000 in staffing, amortized construction costs can be cut to a total of $20 000 per year if two drive-thru are installed simultaneously, instead of one at a time. To complete her analysis, Hart collected 1 month’s worth of arrival and service rates at a competing bank. These data follow:

a) Simulate a 1-hour time period, from 1:00 P.M. to 2:00 P.M., for a single-teller drive-thru.

b) Simulate a 1-hour time period, from 1:00 P.M. to 2:00 P.M., for a two-teller system.

c) Conduct a cost analysis of the two options. Assume that the bank is open 7 hours per day and 200 days per year.

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Interarrival Times for 1000 Observations Time between Arrivals Number of (minutes) Occurrences 1 200 250 3 300 4 150 5 100 Customer Service Time for 1000 Customers Number of Occurrences Service Time (minutes) 1 100 2 150 3 350 4 150 5 150 6 100 2.