CPM prob-5

Activity	Predecessor	Duration (in days)
A	-	6
B	-	4
C	-	7
D	ABC	5
E	ABC	6
F	D	9
G	E	4
H	FG	8
I	FG	6
J	H	7

FG

F starts from D & G starts from E;They start from different nodes, and there is no repetition of either F or G,therefore heads of F&G should be merged.

To analyses ABC we need to break this into three pair of AB, BC & AC

AB

A & B starts from  1st node; They start from same nodes, and they are not repeated, therefore dummy is required from either A to B or B to A

BC

B & C starts from  1st node; They start from same nodes, and they are not repeated, therefore dummy is required from either B to C or C to B

AC

A & C starts from  1st node; They start from same nodes, and they are not repeated, therefore dummy is required from either A to C or C to A

Each pair need dummy, take nay one letter say B, draw DY from A to B & C to B

 

NWD diagram

CPM

Critical path	Duration (in days)
1-3-5-7-8-9	4-5-9-8-7           =33
1-2-3-6-7-8-9	6-0+6+4+8+7      =31
1-4-3-5-7-8-9	7+1+5+9+8+7      =36
1-2-3-5-7-8-9	6+0+5+9+8+7      =35
1-2-3-6-7-9	6+0+6+4+6         =22
1-2-3-5-7-9	6+0+5+9+6=26    =26