Question

Q1. a) Draw a project network using (AOA) method, b) and calculate (EST, EFT, LFT, LST) for each activity, c) and define the critical path. Activity Symbol A B C Predecessor Activity D E F G Duration (Weeks) Nil Nil Nil 5 9 4 B 7 AC C 8 7 D F

Answer 1

From given data of activity and its duration, AOA (Activity On Aerrow) network is drawn as shown below.

m A/co 0 G A → 3 5 5

EFT = EST + Duration

LST = LFT - Duration

Total Float= LFT - EFT

Activity	Duration	EST	EFT	LST	LFT	Total Float	Comment
A	5	0	5	8	13	8
B	9	0	9	0	9	0	Critical
C	4	0	4	5	9	5
D	7	9	16	9	16	0	Critical
E	8	5	13	13	21	8
F	7	4	11	9	16	5
G	5	16	21	16	21	0	Critical

here in activity B, D and G total float is zero thus these are critical activities.

Critical path is B-D-G and the critical duration of the project is 9+7+5= 21 days.