3. Cong Sao Dessert
Cong Sao
Dessert is a
popular chain
dessert shop
in Hong Kong.
4. Fast Facts of Cong Sao Dessert
Capacity of Seats
68
Cooks
3
Waitress
5
Cashier
1
HK$15000
Per Month
Salary of a Waitress
HK$12000
Per Month
Average time for dessert preparation
6 minutes
Per Order
Salary of a Cook
No. of total orders in rush hour
25
Per Hour
No. of take-out orders in rush hour
10
Per Hour
5. Two-Week Daily Order Count
Tue
Wed
Thu
Fri
Sat
Sun
1st week
118
107
108
123
166
239
273
2nd week
114
111
134
124
149
279
267
Mon
Busiest days among a
week: Friday, Saturday
and Sunday
Rush time each day:
9:30 PM to 11: 30PM
7. M/M/3
E q u a & o n s
f o r
m u l & p l e -‐
channel
queuing
wai&ng
model
with
Poisson
arrival
and
exponen&al
service
Times
(M/M/s)
are
complicated.
Series
of
func&ons
used
by
us
are
shown
in
right.
Use
the
M/M/s
Template
in
Excel
to
generate
useful
parameters
for
analysis.
10. Fast Facts
No Way to Increase
Any More!!!
Capacity of Seats
68
Cooks
3
Waitress
5
Cashier
1
HK$15000
Per Month
Salary of a Waitress
HD$12000
Per Month
Average time for dessert preparation
6 minutes
Per Order
Salary of a Cook
No. of total orders in rush hour
25
Per Hour
No. of take-out orders in rush hour
10
Per Hour
11. Three Recommendations
• More Cooks (Cong Sao)
• Delivery Service and
Call & Pickup (Cong Sao)
• Cycle Time Reduction (Customers)
12. More Cooks
• Optimal Number of Cooks
• Trade-off between
Cost of Service (SC) & Cost of Waiting (WC)
13. Total Expected Costs
Costs
Total
Cost
Cost
of
Service
goes
up
as
you
pay
for
more
servers.
Fewer
servers
oJen
means
longer
wai&ng
for
customers.
Costs
of
Wai/ng
goes
down
as
service
increases.
Op&mal
#
of
servers
Number
of
Servers
Many
servers
means
liKle
or
no
wai&ng,
but
higher
service
costs.
Note
that
the
lowest
cost
system
requires
some
customer
wai/ng.
14. How to Measure the SC & WC
• SC – Hourly Wages of a Cook and a Waitress (Cs)
• WC – Hourly wages* of customers# lost in queuing (Ca)
*Information from 2011 Hong Kong Population Census
Average working time are 49 hours per week from
Report of Policy Study on Standard Working Hours,
published by Labour Department of Hong Kong SAR
# Customers here mainly refer to people living in
Hang Hau East, where the dessert shop locates.
17. The optimal number of
4
Cooks is , which means
Cong Sao should hire one
more cook.
18. Delivery Service and Call & Pickup
• No need to wait outside for take-out food
• How to implement
1. Hire Part-time delivery person
2. Cross training is adopted.
• Detailed feasibility analysis
19. Delivery Service
Flowchart for Delivery service (in rush time)
Customer calls in
Delivery Service for local
community should be priced
reasonably or free when
orders are big enough.
Order waits to be
prepared
Order is prepared
Average time=6
minutes
Order is delivered
Average time=20
minutes(round
trip)
Order
waits
to
be
delivered
21. Call & Pickup
• Customers order by phone and pick up desserts by
themselves.
• The accuracy of picking-up time estimation will be
critical. Customers should be clearly informed when
they can pick up their orders.
• Cong Sao can offer 85% to customers.
22. Cycle Time Reduction
• Pre-Order In Queue
1.
2.
3.
4.
Stick latest menus on external walls
make it easy for customer to check out
pre-order or offer self-order sheets
shorten the unnecessary order time
• Re-check Number of Customers
Write down the number of seats required for a group of customers.
They will be allowed in, when it goes to their turn and all of their
members gather.
23. Cycle Time Reduction
• Background Music
More arousing music leads individuals to carry out activities
more quickly or spend less time on activities. Carefully select
background music to make customers eat fast.
• Discount For Fast Eating
Offer Customers 10% discount if they can finish
their desserts within 15 minutes, in peak time.
24. Conclusion
• In this project, we describe a common queuing
situation and present feasible mathematical
models for analysis.
• Shorten queue length outside to improve the
quality of queuing and offer more convenience to
customers.
