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Critical Path Analysis
Activity Durationmins
Shower 3Dry hair 8Fetch car 7Iron clothes 12Dress and make-up
10
Drive to interview
20
Precedence table
Activity Immediately preceding activities
Durationmins
A Shower - 3
B Dry hair A 8
C Fetch car - 7
D Iron clothes - 12
E Dress and make-up
B,D 10
F Drive to interview
C,E 20
The last activities that must be completed
before an activity can begin
Latest finish time
Earliest start time
Activity
Duration
3
BLatest finish time
Earliest start time
Activity
Duration
8 12
Activity B
Dry Hair
Using Labels to Identify the Activity
Activity on Node Network
The network will build up with each mouse click, in the order you would construct it on paper.
0 0
Start
3
A
8
B
7
C
20
F
10
E
12
D
0
End
Nothing precedes A, D or CB follows AE follows B and DF follows E and C
Activity Immediately preceding
activities
Duratio
nmins
A Shower - 3
B Dry hair A 8
C Fetch car - 7
D Iron clothes - 12
E Dress and make-up
B,D 10
F Drive to interview
C,E 20
Activity on Node Network
0 0
Start
0 3
A
3 8
B
0 7
C
22 20
F
1210
E
0 12
D
42 0
End
Activity Immediately preceding
activities
Duratio
nmins
A Shower - 3
B Dry hair A 8
C Fetch car - 7
D Iron clothes - 12
E Dress and make-up
B,D 10
F Drive to interview
C,E 20
Activity on Node Network
0 00
Start
0 43
A
3 128
B
0 227
C
22 4220
F
12 2210
E
0 1212
D
42 420
End
Activity Immediately preceding
activities
Duratio
nmins
A Shower - 3
B Dry hair A 8
C Fetch car - 7
D Iron clothes - 12
E Dress and make-up
B,D 10
F Drive to interview
C,E 20
Activity on Node Network
0 00
Start
0 43
A
3 128
B
0 227
C
22 4220
F
12 2210
E
0 1212
D
42 420
End
Critical activities are activities that cannot run late. For critical activities:
Earliest start time + length of activity = Latest finish time
Activity on Node Network
0 00
Start
0 43
A
3 128
B
0 227
C
22 4220
F
12 2210
E
0 1212
D
42 420
End
The green arrows mark the critical activities, which form the critical path. The critical path(s) must form a continuous route from the start node to the end node.
FloatTotal Floatlatest finish – earliest start – length of activity
Total Float
A 4 – 0 – 3 = 1
B 12 – 3 – 8 = 1
C 22 – 0 – 7 = 15 Activity Immediately preceding
activities
Duratio
nmins
A Shower - 3
B Dry hair A 8
C Fetch car - 7
D Iron clothes - 12
E Dress and make-up
B,D 10
F Drive to interview
C,E 20
-1
1
2
3
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 420X->
|̂Y
DIron
EDress
FDrive
ASh
BDry
CGet Car
0 00
Start
0 43
A
3 128
B
0 227
C
22 4220
F
12 2210
E
0 1212
D
42 420
End
Gantt Chart
Put the critical activities along the bottomThese activities must be started and completed on timeNow put in the non–critical activities at their earliest start timeFinally show the float time
-1
1
2
3
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 420X->
|̂Y
DIron
EDress
FDrive
ASh
BDry
CGet Car
Gantt Chart
Finally how many people are needed?
Obviously one person has to shower, dry and dress
Can another person do the ironing and get the car
2 people are required
