The operations manager of a large plant wishes to overhaul a machine. After conducting a PERT/CPM analysis he has developed the following critical path.

1. Disassemble machine 2. Determine parts that need replacing 3. Find needed parts in inventory 4. Reassemble machine 5. Test machine He has estimated the mean (in minutes) and variances of the completion times as follows.

Activity Mean Variance 1 35 8 2 20 5 3 20 4 4 50 12 5 20 2 Determine the mean and variance of the completion time of the project.