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Calculating Float
Activity Precedence Duration
Start 0
D Start 4
A Start 6
F D, A 7
E D 8G F, E 5
B F 5
H G 7
C H 8
End C, B 0
1. What is the duration of the critical path?
A) 32B) 33
C) 31
D) 35
2. What is the float of activity B?
A) 0
B) 16
C) 10
D) 15
3. What is the float of Activity F?A) 0
B) 5
C) 13
D) 7
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Start EndA B
CD E
F
G H
X
ES EF
LS LF
D
F
1. Precedence Diagram2. Durations
3. Forward Pass (ESEF)
4. Critical Path
5. Float of Critical Path Activities
6. Backward Pass (LFLS)
Q A
1
2
3
1. Precedence Diagram
Calculating Float BEST VIEWED IN SLIDE SHOW MODE
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Start EndA B
CD E
F
G H
X
ES EF
LS LF
D
F
1. Precedence Diagram2. Durations
3. Forward Pass (ESEF)
4. Critical Path
5. Float of Critical Path Activities
6. Backward Pass (LFLS)
Q A
1
2
3
Calculating Float
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A B
CD E
F
G H
Start End
Q A
1
2
3
6 5
84 8
7
5 7
X
ES EF
LS LF
D
F
1. Precedence Diagram2. Durations
3. Forward Pass (ESEF)
4. Critical Path
5. Float of Critical Path Activities
6. Backward Pass (LFLS)
Calculating Float
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A
0
B
CD0
E
F
G H
Start End
X
ES EF
LF
D
F
1. Precedence Diagram2. Durations
3. Forward Pass (ESEF)
4. Critical Path
5. Float of Critical Path Activities
6. Backward Pass (LFLS)
Q A
1
2
3
6 5
84 8
7
5 7
6
4
6 13
4 12
13 18
25 3313 18 18 25
The latestLate Finish of the preceding act iv i t iesdetermines
Early Start
6
4
13
12
0 + 6 = 6
Calculating Float
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A
0 66
B
13 185
C25 338
D0 44
E4 128
F
6 137
G13 185
H18 257
Start End
X
ES EF
LS LF
D
F
1. Precedence Diagram2. Durations
3. Forward Pass (ESEF)
4. Critical Path
5. Float of Critical Path Activities
6. Backward Pass (LFLS)
Q A
1
2
3
The latestEarly Finish of the preceding act iv i t iesdetermines
Critical Path
12
13 18
33
6
4
Calculating Float
B
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A
0 66
B
13 185
C25 338
D0 44
E4 128
F
6 137
G13 185
H18 257
Start End
XES EF
LS LF
D
F
1. Precedence Diagram2. Durations
3. Forward Pass (ESEF)
4. Critical Path
5. Float of Critical Path Activities
6. Backward Pass (LFLS)
Q A
1 B
2
3
0
0
0
0 0
Activities on the Critical Path have ZeroFloat
Calculating Float
A
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A
0 66
B
13 185
C25 338
D0 44
E4 128
F
6 137
G13 185
H18 257
Start End
XES EF
LS LF
D
F
1. Precedence Diagram2. Durations
3. Forward Pass (ESEF)
4. Critical Path
5. Float of Critical Path Activities
6. Backward Pass (LFLS)
Q A
1 B
2
3 A
0
0
0
0 0
0 6
25 33
6 13
13 18 18 25
Activities on the Critical Path have LS=ESand LF=EF
Calculating Float
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A
0 6
0 6
6
0
B
13 185
C25 33
25 33
8
0
D0 44
E4 128
F
6 13
6 13
7
0
G13 18
13 18
5
0
H18 25
18 25
7
0
Start End
Q A
1 B
2
3 A
3328
1 5 5 13
15
1 1
XES EF
LS LF
D
F
1. Precedence Diagram2. Durations
3. Forward Pass (ESEF)
4. Critical Path
5. Float of Critical Path Activities
6. Backward Pass (LFLS)
The earl iestLate Start of the fol low ing act iv i t
iesdetermines Late Finish
33 5 = 28
28 13 = 15
6
5
Calculating Float
D
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A
0 6
0 6
6
0
B
13 18
28 33
5
15
C25 33
25 33
8
0
D0 4
1 5
4
1
E4 12
5 13
8
1
F
6 13
6 13
7
0
G13 18
13 18
5
0
H18 25
18 25
7
0
Start End
XES EF
LS LF
D
F
1. Precedence Diagram2. Durations
3. Forward Pass (ESEF)
4. Critical Path
5. Float of Critical Path Activities
6. Backward Pass (LFLS)
Q A
1 B
2 D
3 A
Calculating Float
What else can we learn from this examp le?
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A
0 6
0 6
6
0
B
13 18
28 33
5
15
C25 33
25 33
8
0
D0 4
1 5
4
1
E4 12
5 13
8
1
F
6 13
6 13
7
0
G13 18
13 18
5
0
H18 25
18 25
7
0
Start End
XES EF
LS LF
D
F
1. Precedence Diagram2. Durations
3. Forward Pass (ESEF)
4. Critical Path
5. Float of Critical Path Activities
6. Backward Pass (LFLS)
Q A
1 B
2 D
3 A
1 1
Project has increased RISKbecause of a Near-Crit ical Path
Calculating Float
