Question

HW12: Project Mgmt。 Saved Problem 15-4 Answer these questions for the following simple set of project tasks. Task times are shown in hours. Skipped eBook Print References a. What is the length of the critical path? 1hou Length of thecriticalpath「 b. What are the earliest start and latest start for E? points Earliest start th/nd hour Latest stat thind hour Sklpped eBook Print References c. What is the latest start for B? test stat th/nd hour d. If all other tasks are completed in their expected durations, will the project length be affected if task B actually takes six hours instead of the expected three? O Yes O No

Answer 1

1. a.

Possible Network paths and their duration are -

ABCH --> 3+3+5+1 = 12
ABEGH --> 3+3+5+3+1 = 15
ADEGH --> 3+6+5+3+1 = 18
ADFGH --> 3+6+6+3+1 = 19

Critical path is the path with longest duration i.e. ADFGH

Length of critical path = 19 hours

1. b.

Earliest Start (ES) = the earliest time when the activity can begin

Earliest Finish (EF) = ES + Activity Duration

Latest Finish (LF) = the latest time by whenthe activity can be finished without changing the project completion duration

Latest Start (LS) = LF - Activity Duration

Slack = LS-ES = LF-EF

Computing using the above gives us the below -

Activity	Predecessor	Duration	ES	EF	LS	LF	Slack
A	-	3	0	3	0	3	0
B	A	3	3	6	7	10	4
C	B	5	6	11	13	18	7
D	A	6	3	9	3	9	0
E	B, D	5	9	14	10	15	1
F	D	6	9	15	9	15	0
G	E, F	3	15	18	15	18	0
H	C, G	1	18	19	18	19	0

ES for E = 9 hours
LS for E = 10 hours

(c) LS for B = 7 hours

(d) If B takes 6 hours, the duration for all paths are -

ABCH --> 3+6+5+1 = 15
ABEGH --> 3+6+5+3+1 = 18
ADEGH --> 3+6+5+3+1 = 18
ADFGH --> 3+6+6+3+1 = 19

Hence, the project length still remains 19 hours and is not impacted