Question

1. 1. Consider the following information:

Activity	Predecessor	Duration (weeks)
A	None	2
B	A	4
C	A	3
D	A	2
E	B	3
F	C	6
G	C, D	5
H	E, F	6
I	G	5
J	H, I	5

Activities B and H can be shortened by a minimum of 2 time units. Which activity would you shorten to reduce the project duration of 2 weeks. Why? (be specific)

Answer 1

ACTIVITY	DURATION	ES	EF	LS	LF	SLACK
A	2	0	2	0	2	0
B	4	2	6	4	8	2
C	3	2	5	2	5	0
D	2	2	4	5	7	3
E	3	6	9	8	11	2
F	6	5	11	5	11	0
G	5	5	10	7	12	2
H	6	11	17	11	17	0
I	5	10	15	12	17	2
J	5	17	22	17	22	0

FORWARD PASS

1. Go from left to right in a network.

2. ES = maximum of the EF value from all the direct predecessors.

3. EF = ES + Duration.

BACKWARD PASS

1. Go from right to left in a network.

2. LF = minimum of the LS value from all the direct predecessors.

3. LS = LF - Duration.

CRITICAL PATH

1. Total slack of all activities should be 0.

2. The total duration of all the activities should be the highest.

3. Slack = LF - EF or LS - ES

CRITICAL PATH & DURATION

A + C + F + H + J = 22

SINCE B IS NOT A CRITICAL ACTIVITY, WE WILL SHORTEN ACTIVITY H BY 2 PERIODS TO GET THE NECESSARY CRASHING, BECAUSE B HAS A SLACK OF 2 AND WOULD INCUR ADDITIONAL COST WITHOUT EVEN AFFECTING THE CRITICAL PATH. a CRITICAL ACTIVITY, ON THE OTHER HAND, WOULD ENABLE US TO SHORTEN THE ENTIRE PROJECT BY 2 PERIODS.