Operation management

Module
3
–
Homework
Questions

Please
submit
your
answers
to
these
homework
questions
via
the
Coursera
website.

Taco
Truck

A
food
truck
serves
customers
during
lunch
hour
by
taking
orders
and
making
fresh
tacos.
There
is
only
one
choice
during
lunch
hour,
since
the
objective
is
to
maximize
the
number
of
customers
served.

The
taco
cooking
works
in
this
manner.
First,
a
batch
of
orders
is
cooked
on
a
grill
by
one
person.
The
cooking
depends
upon
the
number
of
orders
in
the
batch
and
takes
a
little
more
time
if
more
orders
are
in
a
batch.
The
time
taken
to
cook
just
one
order
is
10
minutes.
For
each
additional
order,
it
takes
one
minute
more.
Thus,
cooking
two
orders
in
a
batch
takes
11
minutes,
cooking
three
orders
takes
12
minutes,
and
so
on.

The
other
person
in
the
process
is
accepting
payments.
It
takes
2
minutes
to
receive
the
payment
(one
payment
for
each
order).
Assume
each
order
corresponds
to
one
taco.

TT1.
What
is
the
process
capacity
if
Taco
Truck’s
batch
size
is
4
orders
(in
orders
per
minute)?

TT2.

Calculate
the
batch
size
(in
orders)
at
Taco
Truck
that
will
maximize
the
overall
flow
rate
without
causing
the
customers
to
wait
unnecessarily.

Sarah’s
Organic
Soap
Company

Sarah’s
Organic
Soap
Company
makes
four
kinds
of
organic
liquid
soap:
“regular,”
“lavender,”
“citrus,”
and
“tea
tree.”

Demand
for
the
four
scents
are
150,
120,
75,
and
50
kilograms
per
hour,
respectively.

Sarah’s
production
process
can
produce
any
soap
at
the
rate
of
450
kgs
per
hour,
but
1.5
hours
are
needed
to
switch
between
scents.
During
those
switchover
times,
the
process
doesn’t
produce
any
soap.
Sarah
wants
to
choose
a
production
schedule
that
(i)
cycles
repeatedly
through
the
four
scents,
(ii)
meets
the
required
demand,
and
(iii)
minimizes
the
amount
of
inventory
held.

SOSC1.
How
much
total
set-­?up
time
(in
hours)
will
Sarah
incur
in
one
production
run
(production
cycle)?

SOSC2.
How
many
kgs
of
“regular”
soap
should
Sarah
produce
before
switching
over
to
another
scent?

2

Pooling

P1.
Which
of
the
following
actions
will
provide
you
with
the
biggest
pooling
benefits?

a. Pooling
two
negatively
correlated
demand
streams
b. Pooling
two
independent
demand
streams
c. Pooling
two
positively
correlated
demand
streams