Question

The following activities are part of a project to be scheduled using CPM:

Activity	Immediate Pred	Weeks
A	-	6
B	A	3
C	A	7
D	B, C	2
E	C	4
F	D	3
G	E, F	7

1. Please draw the network.
2. What is the critical path?
3. How many weeks will it take to complete the project?
4. How much slack does each of the activities have?

Question A: Drawing the network

Questions B,C,D use an excel file

Answer 1

ACTIVITY	DURATION	ES	EF	LS	LF	SLACK	CRITICAL
A	6	0	6	0	6	0	YES
B	3	6	9	10	13	4
C	7	6	13	6	13	0	YES
D	2	13	15	13	15	0	YES
E	4	13	17	14	18	1
F	3	15	18	15	18	0	YES
G	7	18	25	18	25	0	YES

FORWARD PASS

We calculate the ES and EF values using a forward pass where the ES of an activity is the maximum EF of all the predecessor activities.

BACKWARD PASS

We calculate the LS and LF values using a backward pass where the LF of the activity is the minimum of all the successor activities.

SLACK

Slack is the value which is determined by subtracting EF from the LF or ES from the LS.

CRITICAL PATH

Critical path is the chain in the project network where the slack value of all the activities is 0, what this means is that any delay in these activities would result in delaying the entire project.

CRITICAL PATH = ACDFG

DURATION OF PROJECT = 25