Question

The following is a table of activities associated with a project at Rafay Ishfaq's software firm in Chicago, their durations and what activities each must precede: Duration(Weeks) Activity Precedes 3 A(start) В.С В 2 5 C F E 2 F F(end) b- The activites on the critical path are: A C- F c- The total project completion time for Rafay Ishfaq's software firm is weeks. d- Determine the slack time for each of the activities. e- What is the total slack for the non critical path(s) in the project? Slack Time (weeks) Activity А C D LL LL

Answer 1

Early Start (ES), Early Finish (EF), Late Start (LS), and Late Finish (LF) for each activity can be computed using the following formulae.

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

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

Slack = LF - EF

Activity	Predecessors	Successors	Duration	ES	EF	LS	LF	Slack
A	-	B, C	3	0	3	0	3	0
B	A	E	2	3	5	4	6	1
C	A	F	5	3	8	3	8	0
E	B	F	2	5	7	6	8	1
F	C, E	-	3	8	11	8	11	0

The critical path is constituted of activities with zero slack.

(b) Activities on the critical path are A-C-F

(c) The total completion time for the project = 11 weeks

(d) and (e)

Activity	Slack
A	0
B	1
C	0
E	1
F	0