Question

Sime Cooperation. is a ship building company. Recently, the company was appointed by the government to build a brand new ship. Table 1.1 shows the process sequence data for the ship development. As an industrial engineer, you need to provide the top management with certain information below:

Activity	Predecessor	Time Estimates (Days)			Cost per day	Crash cost per day
		Optimistic	Most Likely	Pessimistic
		a	m	b
A	-	50	55	60	50	75
B	A	32	34	36	50	75
C	A	68	72	76	80	120
D	B	30	34	38	40	60
E	B, C	56	60	64	60	90
F	E	68	70	78	70	105
G	D, F	100	110	120	60	90

1. Develop a network diagram for the above project. Determine the critical path and minimum project completion time.
2. Calculate the probability that the project can be completed in less than 380 days.
3. ) If the project has to be shortened by three (3) days, determine which activity needs to be crashed and the additional cost involved. Assume there is no limit for crash time and cost per day as well as crash cost per day were based on expected time.

Answer 1

a)

b)

The critical time for this project is 258 days, hence the probability that the project can be completed in less than 380 days is 100 % as the expected time for project completion i.e 380 days is more than the critical time i.e 258 days.

c)

The minimum crash cost per day on the critical activity path i.e 1-2-4-6-7 i.e A-C-E-F is of A i.e 75 days. Hence the additional crash cost for the entire project will be: 75*3 = 225