Question

Consider the following project:

Task ID	Duration (Days)	Predecessors
2	70	-
3	30	2
4	120	3
5	120	2
6	120	5
7	120	3,6
8	150	3,6
9	115	3,6
10	130	7,9
11	90	7,9
12	30	7,9
13	120	7,9
14	75	10
15	30	14
16	85	6
17	165	16
18	90	16
19	90	17,18
20	20	8,11,13,15,19

What is the slack for task 8?

Answer 1

Answer:

step 1	find early start, and early finish from the start of the project for each activity
step 2	Find Maximum EF and keep it as the LF of last activities. Max of EF's is 685
step 3	calculate LS for each activity after calculating its EF

Activity	Duration, D	Early start, ES=Max of early finish of preceding activities	Early finish, EF = ES + D	Late finish, LF= Min of LS of successor activities	Late start, LS= LF - D	Total slack= LF-EF
2	70	0	70
3	30	70	100
4	120	100	220
5	120	70	190
6	120	190	310
7	120	310	430
8	150	310	460	665	515	205
9	115	310	425
10	130	430	560
11	90	430	520
12	30	430	460
13	120	430	550
14	75	560	635
15	30	635	665
16	85	310	395
17	165	395	560
18	90	395	485
19	90	560	650
20	20	665	685	685	665	0

the slack for task 8 is 205