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Leads and Lags

5 minutes 5 Questions

Leads and lags are scheduling techniques used to adjust the timing relationships between activities in a project schedule. They modify the logical relationships defined during activity sequencing to reflect real-world constraints and optimize the schedule. - **Lead:** A lead is an acceleration of …

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PMI-SP - Leads and Lags Example Questions

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Question 1

In a project where Activity A and Activity B have a lag of -5 days and a finish-to-start relationship, which statement best describes their relationship?

Correct Answer: Activity B starts 5 days before Activity A finishes

In project scheduling, when there is a Finish-to-Start (FS) relationship with a negative lag of -5 days, it means the successor activity (Activity B) starts before the predecessor activity (Activity A) finishes, creating an overlap. The negative lag of -5 days indicates that Activity B starts 5 days before Activity A finishes, which is the correct interpretation of this scheduling relationship. The other options are incorrect because: - Starting 5 days after Activity A finishes would represent a positive lag, not a negative one - Mandatory overlapping for exactly 5 days due to resource optimization is not related to the FS-5 relationship description - Starting 5 days after Activity A starts describes a different type of relationship (Start-to-Start) rather than the given Finish-to-Start relationship

Question 2

In a construction project, Activity B was originally planned to start 3 days after Activity A finished. However, after schedule optimization, Activity B can now start when Activity A is 75% complete. What is this 3-day reduction in wait time between activities called?

Correct Answer: Fast tracking through a lead time of 3 days

Fast tracking is the correct project management technique being described in this scenario. When activities that were originally planned to be performed in sequence are rearranged to be performed in parallel, at least partially, this is called fast tracking. In this case, Activity B was supposed to start after Activity A was completed (sequential), but now it starts when Activity A is 75% complete (parallel), creating a lead time of 3 days. The other options are incorrect because: - Schedule compression is a broader term that includes both fast tracking and crashing - Parallel execution is a general term and does not specifically describe the reduction in wait time between activities - Resource leveling actually aims to resolve resource conflicts and typically extends the schedule rather than reducing duration gaps between activities

Question 3

In a large software development project, when you need to model the overlap between testing and development phases using a finish-to-start relationship, what scheduling element represents a 10% completion of the predecessor before the successor can begin?

Correct Answer: A lead of 90%

In project scheduling, when a successor activity can start before its predecessor is completely finished, we use leads and lags to model this relationship. When the requirement states that the successor can begin after 10% completion of the predecessor, this means we need a lead of 90%. This is because: 1. A lead is expressed as a negative time relationship 2. If we need to wait for 10% completion, we can start 90% earlier than the finish 3. Therefore, we use a lead of 90% The other options are incorrect because: - Using a lag duration of 10% would mean waiting for 10% MORE time after the predecessor finishes - A positive lag of 90% would delay the start even further than the finish point - Using project duration as reference instead of the predecessor activity duration is incorrect, as leads/lags are always based on the predecessor activity's duration

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