HOW TO CALCULATE CRITICAL PATH, FREE FLOAT AND TOTAL FLOAT ?

Critical Path Method

Activity	Predecessors	Three time Estimates
		a	m	b
A	---		2
B	A		5
C	A		10
D	A		6
E	B,C,D		9
F	E		4
G	F		3

here we have not putted the values of a and b as it is not required in calculating the critical path, free float and total float.

Step-1: Draw Network Diagram

Step-2: Find Critical Path

P1: A > B > E > F > G = 23

P2: A > C > E > F > G = 28 -> Highest time = critical path

P3: A > D > E > F > G = 24

Step-3: Calculate Early start, late start, early finish and late finish.

SHOWN IN THE DIAGRAM.

Step-4: Calculate Total float and free float.

TOTAL FLOAT=LATE START - EARLY START

Total Float (TF)                                                                   

A	0-0=0
B	7-2=5
C	2-2=0
D	6-2=4
E	12-12=0
F	21-21=0
G	25-25=0

FREE FLOAT OF A ACTIVITY= EARLY START OF NEXT ACTIVITY - EARLY FINISH OF CURRENT ACTIVITY

Free float (ff)

A	2-2=0
B	12-7=5
C	12-12=0
D	12-8=4
E	21-21=0
F	25-25=0