Interfering float is the difference between total float and free float.

Explanation:
Interfering float is an important concept in project management, specifically in the field of scheduling. It refers to the amount of time that a non-critical activity can be delayed without delaying the project. In other words, it is the amount of float that is shared between two or more activities that have a common successor.

Understanding the terms:
In order to understand interfering float, we need to understand the following terms:

1. Total Float: Total float is the amount of time that an activity can be delayed without delaying the project completion date. It is the difference between the late start and early start times of an activity. If an activity has zero total float, it is on the critical path and any delay in its completion will delay the project.

2. Free Float: Free float is the amount of time that an activity can be delayed without delaying the early start of any successor activity. It is the difference between the early finish of an activity and the early start of its successor(s). Free float allows for flexibility in scheduling and can be used to prioritize activities within a project.

Calculating interfering float:
Interfering float is calculated by subtracting the free float from the total float. It represents the float that is shared between two or more activities that have a common successor. Interfering float can affect the scheduling and sequencing of activities and should be carefully managed to avoid delays in project completion.

Example:
Let's consider a simple project schedule with three activities:

Activity A: Duration = 3 days, Total Float = 2 days, Free Float = 1 day
Activity B: Duration = 4 days, Total Float = 5 days, Free Float = 3 days
Activity C: Duration = 2 days, Total Float = 3 days, Free Float = 2 days

In this example, the interfering float between Activity A and Activity B would be 2 days (total float of Activity B) - 1 day (free float of Activity A) = 1 day. This means that Activity A can be delayed by 1 day without delaying the early start of Activity B.

Conclusion:
Interfering float is an important concept in project scheduling. It represents the float that is shared between two or more activities that have a common successor. By understanding and managing interfering float, project managers can optimize scheduling and sequencing to ensure timely project completion.