Environmental Recycling, Inc. must clean up a large automobile tire dump under a
ID: 438073 • Letter: E
Question
Environmental Recycling, Inc. must clean up a large automobile tire dump under a state environmental cleanup contract. The tasks, durations (in weeks), cost, predecessor relationships are shown as follows:
Activity
Predecessor(s)
Normal Time
Crash Time
Normal Cost
Crash Cost
A
-
5
4
$400
$750
B
A
8
6
1600
2200
C
A
7
6
800
1100
D
-
6
5
600
1000
E
B, D, C
8
6
1200
2200
F
D
3
2
800
1000
G
D
3
2
500
650
H
E
4
3
400
600
I
F, G, H
6
5
900
1300
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What is the Earliest start and Earliest finish for all activities left to right?
What is the Latest Finish and Latest start for all activities right to left?
Activity
Predecessor(s)
Normal Time
Crash Time
Normal Cost
Crash Cost
A
-
5
4
$400
$750
B
A
8
6
1600
2200
C
A
7
6
800
1100
D
-
6
5
600
1000
E
B, D, C
8
6
1200
2200
F
D
3
2
800
1000
G
D
3
2
500
650
H
E
4
3
400
600
I
F, G, H
6
5
900
1300
Explanation / Answer
Activity A B C D E F G H I
Earliest start 0 5 5 12 18 18 18 26 30
Earliest finish 5 17 12 18 26 21 21 30 36
Latest start 0 6 5 12 18 27 27 26 30
Latest Finish 5 18 12 18 26 30 30 30 36
Critical path is A-C-D-E-H-I.Completion time = 36. Total normal cost = $6600.
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