Lead and Lag Times and Their Effect on the Critical Path

Correct Answer: Activity C starts 3 days after Activity B finishes, and Activity E starts 2 days before Activity D finishes

In project scheduling, lag and lead times are important concepts that affect the relationship between activities: Lag time (positive): The waiting time that must pass after one activity before the next activity can start. A 3-day lag means you must wait 3 days after the predecessor finishes before starting the successor. Lead time (negative lag): When a successor activity can start before its predecessor activity finishes. A 2-day lead time means the successor can start 2 days before the predecessor finishes. The correct answer accurately describes both scenarios: - The 3-day lag between B and C means Activity C starts 3 days after Activity B finishes - The 2-day lead between D and E means Activity E starts 2 days before Activity D finishes Other options are incorrect because they: - Mix up the order of activities - Confuse start-to-start relationships with finish-to-start relationships - Misinterpret lag and lead times - Present incorrect timing relationships between the activities

Correct Answer: The total project duration increases by 5 days

In schedule network analysis, when a lag is applied to an activity on the critical path with a finish-to-start relationship, the impact on the project schedule is straightforward. Since the activity is on the critical path, it has zero float by definition. Adding a 5-day lag means the successor activity must wait 5 additional days before it can start. This delay propagates through the network since these activities are on the critical path. As a result, the total project duration increases by exactly 5 days. The other answers are incorrect because: - Parallel paths have no bearing on this scenario as we know the activity is on the critical path - Critical path activities do not have float to absorb delays - Lags on critical path activities always affect the project duration since there is no float available to absorb the delay

Correct Answer: Negative lead times reduce the total duration while positive lag times extend the total duration

Lead and lag times affect the schedule network calculations in specific ways: The correct answer captures the exact relationship between lead/lag times and duration: - Negative lead times (starting an activity earlier) reduce the total duration - Positive lag times (waiting period between activities) extend the total duration Why other options are incorrect: Positive lead times would actually increase duration, not decrease it, and negative lag times could create unrealistic scheduling. Lead times and lag times do not automatically offset each other - their impact depends on the specific values and relationships between activities. Lead times applied to non-critical activities would not create multiple critical paths - they might change float values but would not necessarily create new critical paths.