The Stone River Textile Mill was inspected by OSHA and found to be in violation of a number of safety regulations. The OSHA inspectors ordered the mill to alter some existing machinery to make it safer (add safety guards, etc.); purchase some new machinery to replace older, dangerous machinery; and relocate some machinery to make safer passages and unobstructed entrances and exits. OSHA gave the mill only 35 weeks to make the changes; if the changes were not made by then, the mill would be fined $300,000. The mill determined the activities in a CPM/PERT network that would have to be completed and then estimated the indicated activity times, as shown in the following table: Time Estimates (weeks)
Activity Activity Description Activity Predecessor a m b
a Order new machinery — 1 2 3
b Plan new physical layout — 2 5 8
c Determine safety changes in existing machinery — 1 3 5
d Receive equipment a 4 10 25
e Hire new employees a 3 7 12
f Make plant alterations b 10 15 25
g Make changes in existing machinery c 5 9 14
h Train new employees d, e 2 3 7
i Install new machinery d, e, f 1 4 6
j Relocate old machinery d, e, f, g 2 5 10
k Conduct employee safety orientation h, i, j 2 2 2
Construct the project network for this project and determine the following:
a. Expected activity times
b. Earliest and latest activity times and activity slack
c. Critical path
d. Expected project duration and variance
e. The probability that the mill will be fined $300,000