CompTIA Project+ (PK0-005)Project Management ConceptsMedium
A project manager is reviewing the project schedule for a new construction project. Activity A ('Foundation Laying') has an estimated duration of 10 days. Activity B ('Wall Erection') can only start 2 days after 'Foundation Laying' is complete. Activity C ('Roof Installation') can start immediately after 'Wall Erection' is complete. What type of dependency exists between Activity A and Activity B?
- AStart-to-Finish (SF)
- BStart-to-Start (SS)
- CFinish-to-Start (FS) with a lag
- DFinish-to-Finish (FF)
Show answer & explanationAnswer & explanation
Correct answer: C. Finish-to-Start (FS) with a lag
Activity B ('Wall Erection') cannot start until Activity A ('Foundation Laying') is complete, which indicates a Finish-to-Start (FS) dependency. The additional condition that B can only start '2 days after' A is complete signifies a 2-day lag, meaning a delay after the predecessor finishes before the successor can start.
Why the other options are wrong
- A. SF means A cannot finish until B starts, which is the inverse and incorrect.
- B. SS means B can start when A starts, which is incorrect.
- D. FF means B must finish when A finishes, which is incorrect.
Finish-to-Start (FS) Dependency with Lag
A logical relationship where a successor activity cannot start until a predecessor activity has finished, and there's an additional waiting period (lag) after the predecessor's completion before the successor can begin.
- Most common type of dependency.
- Lag is a positive duration of time that must pass before the successor can start.
- Represented as FS+Lag.
Memory trick: FS with a lag is like waiting for paint to dry after a task is done.