Should the Bathroom Counters be Assembled Off-Site? (5 marks)

Half of the duration of the Install Bathroom Fixtures activity is due to installing the bathroom sink and faucet, while the toilet and shower install represents the other half. The selected local plumbing company has mentioned they have been testing a new process where they assemble the bathroom counter with the sink and faucet off-site, then install the already assembled counter and tie-in to the plumbing on-site. By minimizing the time spent under the counter on-site, the counters can often be successfully installed faster. You have mentioned this alternative approach to HQ and while they are interested and would like to be a pilot project for the local supplier, they have expressed concerns that the suppliers minimal experience with this approach would surely involve uncertainty, potentially causing problems with the planned project schedule. They have asked you to investigate and provide a recommendation for which approach they should approve. The costs of both alternatives would be very similar, so the uncertainty of the schedule is the primary focus. Assume the local supplier would work 5 days a week regardless of the approach. The supplier has provided the following details of tasks, sequence, and optimistic, most likely, and pessimistic durations for each task, which would be substituted for 50% of the planned Install Bathroom Fixtures task. Task ID

	Task Description	Immediate Predecessor	Optimistic Duration (days)	Most Likely Duration (days)	Pessimistic Duration (days)
A	Cut counters with sink & faucet openings	-	1.5	2.5	4
B	Attach sinks & faucets to counters	A	1.5	2	3
C	Prep bathrooms with supports & tie-ins	A	2.5	4	5
D	Install assembled counters & tie-in	B,C	1.5	2.5	4.5

a. What is the probability that this alternative off-site counter assembly approach would be faster than 50% of the planned normal duration of the Install Bathroom Fixtures task?

b. What approach do you recommend? Why?