I 94 section 1 OPERATIONS
STRATEGY
ANDMANAGING
CHANGE
ADVANCED PROBLEM
12 Assume the network and data that follow:
NORMAL CRASH
TIME NORMAL TIME CRASH IMMEDIATE
ACTIVITY (WEEKS) COST (WEEKS) COST PREDECESSORS
A 2 Sso 1 $70
B 4 80 2 160 A
C 8 70 4 110 A
D 6 60 5 80 A
E 7 100 6 130 B
F 4 40 3 100 D
G 5 100 4 150 E,F
a. Construct the network diagram.
b. Indicate the critical path when normal activity times are used.
c. Compute the minimum total direct cost for each project duration based on the cost associ-
ated with each activity. Consider durations of 13, 14, 15, 16, 17, and 18 weeks.
d. If the indirect costs for each project duration are $400 (18 weeks), $350 (17 weeks), $300
(16 weeks), $250 (15 weeks), $200 (14 weeks), and $150 (13 weeks), what is the total
project cost for each duration? Indicate the minimum total project cost duration.
CASE: THE CAMPUS WEDDING (A)
. . fIIl!J On March 31 of last year, Mary Jackson burst into the
family living room and announced that she and Larry Adams (her
Father: Ugh!
Mother: And catering! It takes two days to choose the cake and
college boyfriend) were going to be married. After recovering from
the shock, her mother hugged her and asked, "When?" The follow- table decorations, and Jack's Catering wants at least
ing conversation resulted: 10 days' notice prior to the rehearsal dinner (the night
before the wedding).
Mary: April 22.
Mary: Can I wear your wedding dress, Mom?
Mother: What!
Mother: Well,we'd haveto replacesomelace,but youcouldwear
Father: The Adams-Jackson wedding will be the social hit of the it, yes. We could order the lace from New York when we
year. Why so soon?
order the material for the bridesmaids' dresses. It takes
Mary: Because on April 22 the cherry blossoms on campus are eight days to order and receive the material. The pattern
always in full bloom! The wedding pictures will be needs to be chosen first, and that would take three days.
beautiful.
Father: We could get the material here in five days if we paid an
Mother: But honey, we can't possibly finish all the things that need extra $25 to airfreight it.
to be done by then. Remember all the details that were
Mary: I want Mrs. Watson to work on the dresses.
involved in your sister's wedding? Even if we start
tomorrow, it takes a day to reserve the church and Father: But she charges $120 a day!
reception hall, and they need at least 17 days' notice. That
has to be done before we can start decorating the church, Mother: If we did all the sewing, we could finish the dresses in
which takes three days. An extra $100 contribution on 11 days. If Mrs. Watson helped, we could cut that downto
Sunday would probably cut that 17-day notice to 10 days, six days, at a cost of $120 for each day less than 11days.
though. Mary: I don't want anyone but her.
Father: Ugh!
Mother: It would take another two days to do the final fitting.It
Mary: I want Jane Summers to be my maid of honor. normally takes two days to clean and press the dresses,
but that new cleaner downtown could do them in one day
Father: But she's in the Peace Corps, in Guatemala, isn't she? It
if we pay the $30 charge for express service.
would take her 10 days to get ready and drive up here.
Mary: But we could fly her up in two days, and it would cost Father: Everything should be completed by rehearsal night, and
only $500. She would have to be here in time to have her that's only 21 days from now. I bet that will be a busy day.
dress fitted. Mother: We've forgotten something. The invitations.
