Direct answer
Calculate a simple finish-to-start network duration and critical activities from activity durations and predecessors, with clear scope and model limitations.
What to know
- Use consistent units for all inputs.
- Validate zero and negative values before dividing.
- State the forecasting assumption before using an output for a decision.
- Reconcile calculator results with the approved project data date and baseline.
How to apply it
Enter current, controlled project data. Review the formula and model limits before communicating the result, and retain the input values with the analysis.
Formula
Forward pass: EF = ES + duration, where ES is the maximum predecessor EF. Backward pass calculates late dates; activities with zero total float are critical.
Worked example
For A=3, B=4 after A, C=2 after A, and D=3 after B and C, the duration is 10 and the critical path is A → B → D.
Common mistakes
- Mixing currencies or data dates.
- Reporting excessive decimal precision.
- Treating one formula as a guaranteed forecast.
Exam and practice connection
PMP questions can test both calculation and interpretation. Read the wording and identify the requested metric before calculating.