Jude and Pat Strohsal have a crack in their water line and need to replace it. This will require digging up the water line, replacing it, filling the hole, leveling the soil, and reseeding the grass. The Strohsal’s plumber suggests that, because they will have the water line dug up, they also should replace the foot valve. Below are the plumber’s estimates of the time (in hours) necessary to perform each of the activities required?

a. If the plumber and his crew begin working at 7:00 a.m., what time are they expected to finish?
b. The plumber has scheduled another small job at 6:00 p.m. If it takes 1/2 hour to drive from the Strohsal’s to the other job, what is the probability the plumber will be able to make the 6:00 p.m. appointment on time?
c. Jude Strohsal can't bear to see her lawn all dug up so she has decided to visit her mother on the day the work is to be done. Jude wants to return home at 6:45 p.m. What is the probability the work will be complete when she arrives home?

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Activity Description Predecessor Optimistic Most Likely Pessimistic Digging B Replace line CReplace foot valveB D Fill hole 1.5 1.5 5.5 1.5 1.5 Level soil Reseed lawn