Question

1) In a project, activity A, B, and C are the predecessors (or prerequisites) of activity D. The EFTs of activities A, B, and C are week 5, week 7, and week 4, what are the EST and EFT for activity D? Assume that activity D has 6-week task duration. Round your answer to the nearest integer. (Input EST in the first blank and EFT in the second blank.)

2)In a project, activity A, B, and C are the successors of activity D. The LSTs of activities A, B, and C are week 10, week 7, and week 9, what are the LST and LFT for activity D? Assume that activity D has 6-week task duration. Round your answer to the nearest integer. (Input LST in the first blank and LFT in the second blank.)

Answer 1

1. For calculating EST (Early Start time) and EFT (Early Finish time), we must look at forward path.

Predecessors of D are A, B, C.

EFT of activity A = 5 week

EFT of activity B = 7 week

EFT of activity C = 4 week

EST of an activity = Maximum EFT of its predecessor activities

Therefore,

# EST of activity D = 7 weeks

Given that duration of activity D = 6 week

EFT of activity D = Duration + EST of activity D

EFT of activity D = 6 + 7

# EFT of activity D = 13 weeks

2. For calculating LST (Late Start time) and LFT (Late Finish time), we must look at backward path.

Successors of D are A, B, C.

LST of activity A = 10 week

LST of activity B = 7 week

LST of activity C = 9 week

LFT of an activity = Minimum LST of its successor activities

Therefore,

# LFT of activity D = 7 weeks

Given that duration of activity D = 6 week

LST of activity D = LFT of activity D - Duration

LST of activity D = 7 - 6

# LST of activity D = 1 weeks