PMI Scheduling Professional Certification (PMI-SP) Practice Exam

What is the formula used to calculate free float in project scheduling?

1. Successor ES - Activity ES + Duration Activity

2. Successor ES + Activity ES - Duration Activity

3. Successor ES - Activity ES - Duration Activity

4. Successor ES - Activity ES + Duration Activity

The correct answer is: Successor ES - Activity ES + Duration Activity

The formula for calculating free float in project scheduling is based on the start times and duration of activities in a schedule. Free float is defined as the amount of time that a task can be delayed without causing a delay to the early start of any dependent (successor) tasks. The correct formula consists of the early start (ES) of the successor activity minus the early start of the current activity, plus the duration of the current activity. This calculation allows project managers to determine how much flexibility there is in scheduling the current task without impacting subsequent tasks. Using the components of the formula: - The early start of the successor gives you the threshold by which the current activity must be completed for the subsequent task to start on time. - Subtracting the early start of the current activity identifies how much time is available between these two points before the successor is impacted. - Adding the duration of the current activity takes into account the total time it will take to complete the task, providing a clear picture of how much free float exists. This comprehensive approach results in an accurate assessment of free float, which is essential for effective project scheduling and resource management.