Question

Using Table 2.13 below, if the expected time for activity E is changed to nine weeks, by how many weeks will the project's expected completion time increase?
Table 2.13
(All activity times for the project are in weeks.)

Activity	Optimistic Time	Most Likely Time	Pessimistic Time	Immediate Predecessors(s)
A	3	4	5	---
B	5	7	9	---
C	2	3	10	A
D	2	5	8	B
E	1	7	7	B
F	3	5	7	CD
G	7	8	9	DE
H	2	6	10	F

Answer 1

Critical path = Longest path duration of project = BDFH = 23 weeks

Activity	ACTIVITY before	Optimistic (a)	Most likely (M)	Pessimistic (b)	PERT Estimate = (a+4*M+b)/6
A	---	3	4	5	4.00
B	---	5	7	9	7.00
C	A	2	3	10	4.00
D	B	2	5	8	5.00
E	B	1	7	7	6.00
F	CD	3	5	7	5.00
G	DE	7	8	9	8.00
H	F	2	6	10	6.00

New Expected time for E = 9 weeks. The critical path shifts to BEG. New project duration = 7 + 9+ 8 = 24 weeks