My working out: (EST,EFT) times for the activities:
- A: (0,0) B: (0,8)
- C: (3,3)
- D: (10,38)
- E: (10,18)
- F: (18,18)
- G: (25,33)
- H: (58,58)
- I: (25,33)
- J: (45,53)
- K: (118,118)
- Finish: (133,133)
Critical path is: A-C-F-H-K (133)
Therefore the activities than be delayed are out of: B,D,E,G,I,J
Delay times:
- B: 38-8 = 30
- D: 58-38 = 20
- E: 33-10 = 23
- G: 58-33 = 25
- I: 53-33 = 20
- J: 118-53 = 65
Therefore J can be delayed up to 65 days without changing the completion time.
But the answer says D, which is worked out by finding EFT-EST as such:
B: 8-0=8
D: 38-10=28
E: 18-10=8
G: 33-25=8
I: 33-25=8
J: 53-25=8
Can someone please check this and let me know how to correctly find delay times, using EST and EFT.
If you add up the path leading to the start of K going through J you get 10d+ 15d + 20d + 65d = 110d, doing the same thing along the path going through H we get 3d + 15d + 40d + 60d = 118d, so as you can see here we can delay J by 8d and still fall under/at the minimum time.
Now, at the start of H the path going through F takes 58d (3d + 15d + 40d) H cannot start until D completes which it will do in 10 + 20 = 30d so we can delay D by 28d and still be at the minimum time for the whole project.Hence D is the answer