Question

Mauritius Pharmaceuticals Ltd was undertaking a project for reviewing the packaging of its saline drips. The activities and the duration of each activity are shown in the table below.

Activity Completion time (weeks)

ACTIVITY	Completion time (weeks)
A	6
B	9
C	8
D	5
E	10
F	6
G	14
H	11
I	9

The immediate precedence relationships are:

 Activities D and E follow activity B.

 Activities A and D follow activity C.

 Activities G and H follow activity E.

 Activities C and I follow activity F.

(i) Draw an appropriate network diagram to correctly represent the project.

(ii) Calculate the Earliest start time, the Earliest finishing time, the Latest start time, the Latest finishing and the Float for each activity.

(iii) Identify the critical path and calculate the overall project completion time.

(iv) Explain clearly (with reasons) the effect upon the overall project Completion time, if the completion time for activity B increases from 9 weeks to 12 weeks while at the same time the completion time for activity H increases from 11 weeks to 14 weeks. Identify what action if any, which the project manager has to take

Answer 1

ACTIVITY	DURATION	ES	EF	LS	LF	SLACK
A	6	14	20	27	33	13
B	9	0	9	0	9	0
C	8	6	14	19	27	13
D	5	14	19	28	33	14
E	10	9	19	9	19	0
F	6	0	6	13	19	13
G	14	19	33	19	33	0
H	11	19	30	22	33	3
I	9	6	15	24	33	18

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 & DURATION

B + E + G = 33

2. WITH B = 12 AND H = 14, THE PREVIOUS CRITICAL PATH WILL CHANGE AND NOW BEG AND BEH WOULD BOTH BE CRITICAL WITH A PROJECT DURATION OF 36, SINCE BOTH H AND G TAKE THE SAME DURATION TO BE COMPLETED.

ACTIVITY	DURATION	ES	EF	LS	LF	SLACK
A	6	14	20	30	36	16
B	12	0	12	0	12	0
C	8	6	14	22	30	16
D	5	14	19	31	36	17
E	10	12	22	12	22	0
F	6	0	6	16	22	16
G	14	22	36	22	36	0
H	14	22	36	22	36	0
I	9	6	15	27	36	21

ST END