Forward Pass

5 minutes 5 Questions

Forward pass is a technique used to estimate the early start and early finish dates for the uncompleted portions of all network activities. This is done by moving forward through the project's network diagram, with the objective of identifying the project timeline. It's an important concept in unde…

Understanding the Forward Pass in Critical Path Method

What is it:
Forward Pass refers to the process of determining the earliest start and finish times for each activity within a project network diagram. It forms the critical component of the Critical Path Method (CPM), a popular scheduling technique to devise plans and manage complex projects.

Why is it important:
Garnering an understanding of Forward Pass is pivotal: it helps in identifying critical or non-critical activities, evaluating project duration, discerning resource usage and offering insights into potential project delays whilst streamlining workload distribution.

How it works:
The process begins with the first activity, setting its early start (ES) as zero. For each subsequent activity, its early finish (EF) is determined by adding its duration to the ES. Given multiple predecessors, forward pass uses the maximum EF of them for its ES. The last activity's EF is the project completion time.

How to answer questions in an exam:
One must begin by comprehensively detailing the concept of Forward Pass, citing its role in CPM along with its advantages. Following this, apply the concept to the given problem, stating step-by-step calculations and logical reasoning. Finally, summarize the question’s solution.
Note: Diagrams may aid in understanding/representation.

Exam Tips:
Understanding Forward Pass thoroughly is crucial. To answer effectively:
1. Define Forward Pass extensively, providing examples where possible.
2. Understand the question carefully. Extract Activity durations and precedences.
3. Draw a CPM network diagram; denote ES and EF for each activity.
4. Perform a step-by-step Forward Pass, justifying your calculations.
5. Conclude by stating the project duration and critical path, emphasizing the role of Forward Pass therein.
Remember practice and organization are key. A neat, logical presentation, demonstrating competency can fetch good grades.

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Question 1

You are working on a project where the activity has an earliest start time (EST) of 5 days and a latest start time (LST) of 10 days. What is the total float of this activity?

0 days 5 days 15 days 10 days

Correct Answer: 5 days

The total float of an activity in project management is the amount of time that you can delay the activity without delaying the project. More specifically, it's the difference between the latest start time (LST) and the earliest start time (EST). In this case, the LST is 10 days and the EST is 5 days. By subtracting the EST from the LST (10 days - 5 days), we find that the total float is 5 days. The answer indicating 10 days is incorrect as it's the LST, not the total float. The answer indicating 15 days is incorrect as it appears to be adding the EST and LST, which is not how total float is calculated. The answer indicating 0 days is incorrect as it would mean there is no time to delay, which contradicts the given EST and LST.

Question 2

You are managing a project with an activity that has an earliest start time (EST) of 4 days and a duration of 6 days. What would be the earliest finish time (EFT) for this activity in a forward pass calculation?

9 days 10 days 11 days 8 days

Correct Answer: 9 days

Given: - Earliest start time (EST) = 4 days (meaning the activity can start on the 4th day) - Duration = 6 days To calculate the earliest finish time (EFT), we need to consider that the activity starts on the 4th day and lasts for 6 days. The finish time will be the day before the next EST. EFT = (EST - 1) + Duration Now, let's calculate the earliest finish time: EFT = (4 - 1) + 6 EFT = 3 + 6 EFT = 9 days

Question 3

Assume you manage a project and the Final activity is planned to finish on the 30th day (EFT). The activity has a duration of 10 days. What's the earliest start time (EST) in a forward pass calculation?

10 days 40 days 20 days 30 days

Correct Answer: 20 days

The earliest start time (EST) for an activity in a project can be calculated by subtracting the duration of the activity from its earliest finish time (EFT). Here, the final activity is planned to finish on the 30th day, which is the EFT. The duration of the activity is given as 10 days. To find out the EST, we subtract the duration from the EFT. So, 30 (EFT) - 10 (duration) = 20 days. This means that the earliest this final activity can start is on the 20th day. The other options are incorrect because they don't follow this calculation. An EST of 10 days would mean the activity needs to finish by the 20th day, not the 30th, an EST of 40 days would be after the planned EFT, and an EST of 30 days would imply that the activity has no duration, which is not possible.

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