Chapter 6 - Exercise 2

Consider Table 6-3, Network diagram data for a small project. All duration estimates or estimated time are in days; and the network proceeds from Node 1 to Node 9.













2b. All the possible paths for Table 6-3

Path 1: A-B-E-H-K Length: 2+2+2+2+2 = 10 Days
Path 2: A-C-F-H-K Length: 2+3+3+2+2 = 12 Days
Path 3: A-C-F-I-J-K Length: 2+3+3+5+1+2 = 16 Days
Path 4: A-D-G-J-K Length: 2+4+6+1+2 = 15 Days

2c. Since the critical is the longest path, Path 3 A-C-F-I-J-K is the critical path which takes 16 days

2d. The shortest possible time to complete the project is Path 1 A-B-E-H-K which takes 10 days

2e.

Pert Introduction Activities:

Q1 Answer:

Path 1: A-B-C-E-I Length: 2+3+1+4+3 = 13 Days
Path 2: A-B-D-F-I Length: 2+3+3+3+3 = 14 Days
Path 3: A-G-H-I Length: 2+2+5+3 = 12 Days

Since the critical path is the longest path, Path 2 A-B-D-F-I is the critical path which takes 14 days

Q2 Answer:

What is the slack time for tasks, C, D and G?The slack time for task C is 1 day.

Answer explained below.

The node before task C splits off to another task which is task D. This means both tasks are being done at the same time. Task C = 1 + Task E = 4 = 5 days. Task D = 3 + Task F = 3 = 6 days. Therefore Task C or E can have an extra 1 day to finish.

Task D cannot have any slack or float time because it is part of the critical path as the path needs to run on time. The slack time for task G is 2 days because it requires Path B,D,F to be finish which takes total of 9 days where task G and H takes are total of 7 days.

Q3 Answer:
Task C would no impact on the completion date. Both Task C and E have a total of 1 slack day available. This means if Task C started a day late then task E would be able to start a day late also providing Task C has been completed.

Q4 Answer:
The critical path is still required to be completed. Hence having said this there isn’t any shortcut. The project manager would require allocating more resources or asking the project team to complete overtime work. This also depends on the nature of scope.

Q5 Answer:
Since both task D and F have been shorten by one day each making it a total of 2 days reduction then therefore it is not the critical path. Referring to Q1 answers, Path 1 A,B,C,E,I is the critical path because it takes 13 days whereas the old path takes 12 days to complete.

Gantt Introduction Activities:

Q1 Answer:
Task 7 is the first milestone for the project which is Sign Contracts.


Q2 Answer:
The alterations cannot commence before Monday 11th December therefore make its task 8 – Prepare site. This means there can two paths.
Path 1 – Task 8, 9, 11, 12 = 7 days
Path 2 – Task 8,9,10,12 = 6 days

There is 1 days difference between both tasks but because we didn’t include weekends Path 2 has 3 slacks days and Path 1 can have 2 slacks if they run into any problems.

Q3 Answer:
Due to the cabling being delayed from the 14th to the 18th the project will still be completed on time. The project final milestone requires to be finished by the 21st December. Installing cabling only takes 3 days. Having said the project manager could allow overtime still.

Q4 Answer:

The project manager would have to ask what options he/she have. This is purely common sense. Project Manager may ask the team to work longer hours, hire additional contractors or reducing the time for other task in the project.