THIN K IN G A N A LY T I CA LLY
Pizza delivery
BY JOHN TOCZEK
John Toczek is the senior director
of Decision Support and Analytics for
ARAMARK Corporation in the Global
Operational Excellence group. He
earned a bachelor of science degree
in chemical engineering at Drexel
University (1996) and a master’s
degree in operations research from
Virginia Commonwealth University
(2005). He is a member of INFORMS.
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As the owner of a pizza delivery restaurant, you are
constantly looking for ways to keep costs low while
maintaining quality service. Because your profit margins
are thin, you’d like the number of delivery drivers to be as
low as possible.
You receive orders from customers at an inter-arrival
time of six minutes exponentially distributed. A driver can
pick up one order, deliver it to a customer and return back to
the restaurant in 20 to 60 minutes, equally distributed.
The corporate office mandates that you must have
an average order delivery time of less than 60 minutes.
Some deliveries can be more than 60 minutes and some
can be under 60 minutes, but on average they must be
below one hour.
You may hire as many drivers as you like. But hiring
too many drivers will cause your payroll to be unnecessarily high and too few drivers will put you over the 60-minute
delivery requirement. Assume that a driver can only deliver
one order per round trip.
Question: How many drivers are needed in order to
keep average delivery times under one hour?
Send your answer to [email protected] by May 15.
The winner, chosen randomly from correct answers, will
receive a $25 Amazon Gift Card. Past questions can be
found at puzzlor.com.
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