1. Given the data in bellow Table, what is the probability that the project will be completed in 32 days or less? What is the probability that the project will take longer than 32 days?
2. 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 Strohsals' plumber suggests that, because they will have the water line dug up, they also should replace the foot valve. Following are the plumber's estimates of the time (in hours) necessary to perform each of the activities required.
|
Activity
|
Description
|
Predecessor
|
Optimistic (Best Case)
|
Most Likely
|
Pessimistic(WorstCase)
|
|
A
|
Digging
|
-
|
2
|
3
|
4
|
|
B
|
Replace line
|
A
|
1
|
1.5
|
2
|
|
C
|
Replace foot valve
|
B
|
.5
|
1
|
1.5
|
|
D
|
Fill hole
|
C
|
1.5
|
2
|
5.5
|
|
E
|
Level soil
|
D
|
.5
|
1
|
1.5
|
|
F
|
Reseed lawn
|
E
|
.4
|
.5
|
.6
|
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 Strohsals' 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?