Question

Given below are the durations of and the precedence relationships among the activities required to compute a project.

1) construct an AOA network of the project

2)what is the critical path? determine the expected duration of the project.

3)compute the standard deviation of the critical path

		Duration(days)
Activity	pre-decessor(s)	a	m	b
A	-	4	7	12
B	A	6	9	13
C	A	5	7	9
D	B,C	3	5	8
E	B	7	8	10
F	A	2	3	5
G	E	6	7	9
H	D,I	2	3	4
I	F	8	10	14
J	G,H	4	6	10

Answer 1

Using PERT method

Activity	pre-decessor(s)	a	m	b	t = (a+4m+b)/6
A	-	4	7	12	7.33
B	A	6	9	13	9.17
C	A	5	7	9	7.00
D	B,C	3	5	8	5.17
E	B	7	8	10	8.17
F	A	2	3	5	3.17
G	E	6	7	9	7.17
H	D,I	2	3	4	3.00
I	F	8	10	14	10.33
J	G,H	4	6	10	6.33

The network diagram is drawn.

The critical activities will have slack = 0. Slack = LST - EST

The critcial path is A -> B -> E -> G - > J

The duration of the project is 38.17 days.

Only the Standard deviation of the critical activities accounts to the standard deviation of the entire project.

Activity	a	m	b	S.D = (b-a)/6
A	4	7	12	1.33
B	6	9	13	1.17
E	7	8	10	0.50
G	6	7	9	0.50
J	4	6	10	1.00
			Total S.D	4.50