In: Operations Management
question 1
The following table provides a description for the project Z.
Activity | Duration | Predecessor | Cost to crash by 1 day | Max Days to Crash |
A | 5 | - | $ 300 | 1 |
B | 3 | - | $ 100 | 1 |
C | 4 | A | $ 100 | 1 |
D | 3 | A | $ 200 | 2 |
E | 4 | B | $ 400 | 3 |
F | 2 | D, E | $ 500 | 2 |
G | 4 | E | $ 300 | 3 |
H | 3 | C | $ 100 | 2 |
1. What is the critical path of this project?
2. What is the duration of this project? (before crashing)
3. If your task is to crash this project by 2 days, what is the most efficient cost of doing it? (Just input the number with no decimals or dollar signs
question 2
The expected duration of the project (average) is 30 days and variance is 16.
1. What is the probability that the project will be completed on day 32 or earlier?
2. Suppose the official deadline for the project is 34 days. What is the probability that the project will be delayed?
question 3
A restaurant has tracked the number of meals served at lunch over the last four weeks. The data show little in terms of trends, but do display substantial variation by day of the week. Use the following information to determine the seasonal (daily) indices for this restaurant.
Week |
||||
Day |
1 |
2 |
3 |
4 |
Sunday |
40 |
35 |
39 |
43 |
Monday |
54 |
55 |
51 |
59 |
Tuesday |
61 |
60 |
65 |
64 |
Wednesday |
72 |
77 |
78 |
69 |
Thursday |
89 |
80 |
81 |
79 |
Friday |
91 |
90 |
99 |
95 |
Saturday |
80 |
82 |
81 |
83 |
1. ALL POSSIBLE CHAINS
ACH = 12
ADF = 10
BEG = 11
BEF = 9
CRITICAL PATH = LONGEST PATH = ACH = 12
CRASHING
WE WILL CRASH FROM THE LOWEST CRASH PER PERIOD ACTIVITY THAT IS ON THE CRITICA PATH
ACTIVITY |
NORMAL TIME |
COST / PERIOD |
TIMES CRASHED |
# CRASH |
CRASH COST |
A |
5 |
300 |
0 |
||
B |
3 |
100 |
1 |
2ND |
100 |
C |
4 |
100 |
0 |
||
D |
3 |
200 |
0 |
||
E |
4 |
400 |
0 |
||
F |
2 |
500 |
0 |
||
G |
4 |
300 |
0 |
||
H |
3 |
100 |
2 |
1ST AND 2ND |
200 |
MOST EFFICIENT COST = 200 + 100 = 300
2. A. VARIANCE = 16
STANDARD DEVIATION = SQRT(VARIANCE) = SQRT(16) = 4
EXPECTED TIME = 30
DUE TIME = 32
Z = (DUE TIME - EXPECTED TIME) / STANDARD DEVIATION OF CRITICAL PATH)
Z = (32 - 30) / 4 = 0.5
PROBABILITY FOR A Z VALUE OF 0.5 = NORMSDIST(0.5) = 0.6915 OR 69.15%
B. VARIANCE = 16
STANDARD DEVIATION = SQRT(VARIANCE) = SQRT(16) = 4
EXPECTED TIME = 30
DUE TIME = 34
Z = (DUE TIME - EXPECTED TIME) / STANDARD DEVIATION OF CRITICAL PATH)
Z = (34 - 30) / 4 = 1
PROBABILITY FOR A Z VALUE OF 1 = NORMSDIST(1) = 0.8413
MORE THAN 34 = 1 - 0.8413 = 0.1587 OR 15.87%
3. AVERAGE OVERALL DEMAND = AVERAGE OF ALL DEMAND VALUES IN ALL SEASONS = 69.7143
AVERAGE PERIODIC DEMAND = SUM OF DEMAND IN A PARTICULAR PERIOD / N, WHERE N = NUMBER PERIODS TAKEN INTO CONSIDERATION
SEASONAL INDEX = AVERAGE PERIODIC DEMAND / AVERAGE DEMAND
PERIOD |
AVG PERIOD DEMAND |
AVG DEMAND |
SEASONAL INDEX |
1 |
40 + 35 + 39 + 43 / 4 = 38 |
69.7143 |
38 / 69.7143 = 0.545 |
2 |
54 + 55 + 51 + 59 / 4 = 53.3333 |
69.7143 |
53.3333 / 69.7143 = 0.765 |
3 |
61 + 60 + 65 + 64 / 4 = 62 |
69.7143 |
62 / 69.7143 = 0.889 |
4 |
72 + 77 + 78 + 69 / 4 = 75.6667 |
69.7143 |
75.6667 / 69.7143 = 1.085 |
5 |
89 + 80 + 81 + 79 / 4 = 83.3333 |
69.7143 |
83.3333 / 69.7143 = 1.195 |
6 |
91 + 90 + 99 + 95 / 4 = 93.3333 |
69.7143 |
93.3333 / 69.7143 = 1.339 |
7 |
80 + 82 + 81 + 83 / 4 = 81 |
69.7143 |
81 / 69.7143 = 1.162 |
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