Question

2- Consider the AON network illustrated below: B G H A F Activity A B с D E F Duration 5 3 7 6 2 3 4 5 H a) Calculate the project completion time b) What is the critical path? c) Calculate the slack time for each activity.

Answer 1

Use the critical path method to find the early and late start and finish times as follows:

Forward Pass:

ES of the starting activities = 0
ES of all other activities = Max. (EF of their immediate predecessors)
EF of an activity = Its ES + Its duration

Backward Pass:

LF of ending activities = Max. (All the EFs)
LF of all other activities = Min. (LS of their immediate successors)
LS of an activity = Its LF - Its duration

Total slack (or, float) = LF - EF for each activity.

Activity	Duration	ES	EF	LS	LF	Slack
A	5	0	5	0	5	0
B	3	5	8	9	12	4
C	7	5	12	5	12	0
D	6	12	18	12	18	0
E	2	8	10	16	18	8
F	3	12	15	15	18	3
G	4	18	22	18	22	0
H	5	22	27	22	27	0

(a)

The project competition time = LF of the finishing activity 'H' = 27

(b)

The critical path of a project is composed of activities with zero total slack. So, it's A-C-D-G-H.

(c)

Already there in the table.