25 Questions — PMI – PMI-SP : Certified Scheduling Professional - Domain 2 - Schedule Planning and Development

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1. 1 A project manager is calculating the uncertainty of a task with an optimistic duration of $6$ days, a most likely duration of $10$ days, and a pessimistic duration of $20$ days. What is the variance of this activity using the Beta-PERT distribution?

   Recall that variance is the square of the standard deviation in the PERT formula.

   $5.44$ days

   The standard deviation is calculated as $\sigma = \frac{P - O}{6}$, which is $\frac{20 - 6}{6} = 2.33$, and the variance is the square of the standard deviation, resulting in approximately $5.44$.

   • ✗ $2.33$ days

     This value represents the standard deviation of the activity, not the variance, which requires squaring the standard deviation.

   • ✗ $11$ days

     This value is the expected duration ($EAD$) rather than a measure of spread or uncertainty.

   • ✗ $14$ days

     This represents the range of the activity ($P - O$), which is only the numerator of the standard deviation formula.

2. 2 An activity on the critical path has a duration of $15$ days. To shorten the project, the scheduler crashes the activity by adding resources, reducing it to $10$ days at a cost of $\$500$ per day. However, a parallel path now has a total float of $-2$. What is the primary risk in this scenario?

   Consider how shortening the longest path affects the float of other sequences in the network.

   The parallel path has become the new critical path, and the project is still behind.

   Crashing one path can reduce its duration to the point where a previously non-critical path becomes critical and potentially negative if the new duration is still too long.

   • ✗ The original critical path now has excessive free float.

     Activities on a path with negative or zero float do not have free float; rather, the other path has simply limited the project's recovery.

   • ✗ Crashing was ineffective because it was not performed on an effort-driven activity.

     While crashing requires effort-driven tasks, the negative float on the parallel path indicates the bottleneck has shifted, not that the resources failed to reduce the task duration.

   • ✗ Resource leveling must be performed to remove the negative float.

     Resource leveling usually extends the schedule rather than resolving negative float caused by logic or duration constraints.

3. 3 In a network diagram using the $0$-start format, Activity A has an $ES$ of $10$ and a duration of $5$. Activity B is a successor with a Finish-to-Start relationship and a lag of $+3$. What is the $ES$ of Activity B?

   Calculate the finish time of the first activity before applying the delay.

   $18$

   In $0$-start logic, $EF = ES + Duration$ ($10 + 5 = 15$), and the successor $ES$ is the $EF$ of the predecessor plus the lag ($15 + 3 = 18$).

   • ✗ $15$

     This value ignores the lag of $+3$ which must be added to the early finish of the predecessor.

   • ✗ $13$

     This incorrectly adds the lag to the early start of the predecessor instead of the early finish.

   • ✗ $21$

     This might result from using $1$-start logic and double-counting the start day or the lag period.

4. 4 Which statement best describes the difference between a Level of Effort (LOE) activity and a Hammock activity?

   Look at the flexibility of logical relationships permitted for each type.

   Hammocks are confined to SS and FF relationships, while LOEs can use any relationship type.

   LOEs support work over time and can be linked variously, whereas a hammock is specifically a bridging activity defined by its start-to-start and finish-to-finish links.

   • ✗ LOEs appear on the critical path, while hammocks never do.

     Neither LOE nor hammock activities should typically drive the project end date or reside on the critical path.

   • ✗ LOEs have discrete deliverables, whereas hammocks do not.

     By definition, LOE activities do not produce discrete deliverables; they are supportive in nature.

   • ✗ Hammocks are manually estimated, while LOE durations are always calculated by the tool.

     Both types typically have durations derived from the activities they support or bridge rather than being fixed estimates.

5. 5 If an activity has a Total Float ($TF$) of $10$ days and a Free Float ($FF$) of $0$ days, what occurs if the activity is delayed by $5$ days?

   Distinguish between the impact on the next activity versus the impact on the final project milestone.

   The start of the immediate successor will be delayed, but the project finish date will remain unchanged.

   Free Float of $0$ means any delay impacts the successor, but a Total Float of $10$ means the project end date is protected for up to $10$ days.

   • ✗ The project finish date will be delayed by $5$ days.

     The project finish is only delayed if the delay exceeds the Total Float, which is $10$ days.

   • ✗ Neither the successor nor the project finish will be affected.

     Because the Free Float is $0$, the successor is immediately affected by any delay in the predecessor.

   • ✗ The activity will automatically become part of the critical path.

     An activity only becomes critical when its Total Float is reduced to zero or less.

6. 6 A scheduler observes that an activity has been performed 'Out-of-Sequence' (OOS). Which approach is recommended as a good practice to maintain schedule validity?

   Consider which method ensures that remaining work still respects its required predecessors.

   Use the Retained Logic method and resolve the logic conflict.

   Retained Logic respects the original dependencies, preventing unrealistic finish dates often produced by the Progress Override method.

   • ✗ Apply Progress Override to reflect the actual parallel work performed.

     While Progress Override reflects what happened, it often invalidates future logic and produces overly optimistic forecasts.

   • ✗ Delete the predecessor relationship since work has already started.

     Deleting logic without analysis can create 'open ends' and ruin the integrity of the network diagram.

   • ✗ Convert the activity into a Level of Effort (LOE) task.

     LOE tasks are for supportive work and are not an appropriate way to handle discrete work that was started out of sequence.

7. 7 During a backward pass, Activity C has two successors: Activity D ($LS = 20$) and Activity E ($LS = 25$). If the duration of Activity C is $5$ days, what is the Late Finish ($LF$) of Activity C?

   Identify the most restrictive constraint when working from the end of the project toward the beginning.

   $20$

   The Late Finish ($LF$) of a predecessor is the minimum of the Late Starts ($LS$) of all its successors to ensure no successor is delayed.

   • ✗ $25$

     Choosing the maximum would delay Activity D, violating the definition of the backward pass.

   • ✗ $15$

     This value represents the Late Start of Activity C ($20 - 5$), not its Late Finish.

   • ✗ $45$

     This appears to be a summation of values, which is not used in backward pass logic.

8. 8 A scheduler is using a Start-to-Finish (SF) relationship. Which scenario correctly describes the logic of this relationship?

   Focus on the specific dependency between the 'start' of one task and the 'finish' of another.

   The successor task cannot finish until the predecessor task has started.

   SF logic dictates that the start of the first activity triggers the potential completion of the second, often used in shift handovers.

   • ✗ The successor task cannot start until the predecessor task has finished.

     This describes the most common Finish-to-Start (FS) relationship.

   • ✗ The successor task cannot finish until the predecessor task has finished.

     This describes a Finish-to-Finish (FF) relationship.

   • ✗ The predecessor and successor must happen simultaneously.

     Simultaneity is not a specific logical dependency type but can be modeled using SS and FF combinations.

9. 9 A project involves a geographically distributed team with different local holidays. The project manager insists on using a single global calendar. What is the most likely negative consequence?

   Think about how non-working days impact the availability of resources to complete tasks.

   Float calculations and critical path analysis will be inaccurate for local team members.

   Using one calendar for diverse teams ignores local non-working periods, leading to unrealistic start/finish dates and incorrect float values.

   • ✗ The scheduling tool will be unable to calculate a backward pass.

     Tools can calculate the pass, but the data used (the calendar) will be fundamentally flawed for the actual work being performed.

   • ✗ The project will automatically have zero total float.

     Float is a result of logic and duration; a single calendar does not force float to zero, though it makes the resulting number untrustworthy.

   • ✗ Resource leveling will be impossible to perform.

     Leveling is still possible, but it will allocate resources to work on days they are not actually available (e.g., local holidays).

10. 10 Which schedule compression technique is most likely to increase the project's 'risk vectors' and potential for rework without necessarily increasing immediate costs?

    Identify the method that relies on parallelizing tasks that were originally sequential.

    Fast Tracking

    Fast tracking involves overlapping sequential activities, which does not add resources (cost) but increases risk because tasks start without complete information from predecessors.

    • ✗ Crashing

      Crashing specifically focuses on adding resources to reduce duration, which typically increases costs but keeps the sequential logic intact.

    • ✗ Resource Leveling

      Resource leveling often extends the project duration to resolve over-allocations, rather than compressing the schedule.

    • ✗ Scope De-scoping

      While reducing scope shortens the project, it is not a schedule compression technique; it is a change in deliverables.

11. 11 An activity has an Optimistic duration of $4$ days, a Most Likely duration of $7$ days, and a Pessimistic duration of $16$ days. What is the Expected Activity Duration ($EAD$) using the Beta distribution?

    Apply the weighted average formula that gives four times more importance to the most probable outcome.

    $8$ days

    Using the formula $EAD = \frac{O + 4M + P}{6}$, we get $\frac{4 + 28 + 16}{6} = 8$.

    • ✗ $9$ days

      This is the result of the Triangular distribution formula: $\frac{O + M + P}{3} = \frac{27}{3} = 9$.

    • ✗ $7$ days

      This is simply the Most Likely duration, which does not account for the weighted influence of the other estimates.

    • ✗ $10$ days

      This value does not correspond to standard PERT calculation methods for these inputs.

12. 12 What is a 'Near-Critical Path' and why is it significant in schedule management?

    Consider paths that have just a small amount of slack remaining.

    A path with very low total float that could easily become the critical path if delayed slightly.

    Vigilant monitoring of near-critical paths is essential because minor perturbations can switch the critical path to a new sequence of activities.

    • ✗ A path that is physically close to the critical path in the WBS structure.

      Path criticality is a function of logical dependencies and float, not the physical or organizational grouping of tasks.

    • ✗ A path consisting solely of Level of Effort (LOE) and summary activities.

      LOE activities should not drive the critical path or be the basis for path criticality analysis.

    • ✗ The path with the highest standard deviation in a PERT analysis.

      While standard deviation indicates risk, the near-critical path is defined by its low float relative to the project completion date.

13. 13 In the context of Precedence Diagramming, what is an 'Open End' and why is it generally discouraged?

    Think about activities that are not connected at one end to the rest of the schedule network.

    An activity missing either a predecessor or a successor, which breaks the flow of logic and float calculations.

    Open ends create gaps in the logic that prevent the tool from calculating an accurate critical path and total float for the project.

    • ✗ The conclusion of a project phase without a formal sign-off.

      While lack of sign-off is a procedural issue, an 'open end' in scheduling refers specifically to the network logic structure.

    • ✗ A task that has been started but not finished due to resource shortages.

      Incomplete tasks are part of status reporting; open ends refer to the underlying plan's lack of logical links.

    • ✗ An activity that uses a lag instead of a discrete task duration.

      Lags are relationship modifications, not 'open ends,' though their misuse is also discouraged.

14. 14 If you are crashing a schedule to meet a deadline, which activities should you target first?

    Identify where duration reduction actually translates into a faster project completion date.

    Critical path activities with the lowest cost-per-day for compression.

    Crashing non-critical activities does not shorten the project; targeting the cheapest critical activities ensures the most cost-effective reduction.

    • ✗ Any activity with a high duration and high cost.

      Focusing on cost or duration alone ignores whether the activity actually constrains the project's finish date.

    • ✗ Activities with the largest amount of free float.

      Activities with free float are by definition non-critical, so crashing them provides zero benefit to the overall project duration.

    • ✗ Level of Effort (LOE) activities across the entire project.

      LOEs support work and do not have discrete durations that, when shortened, reduce the project's finish date.

15. 15 What is the primary difference between Resource Leveling and Resource Smoothing?

    Focus on which technique is allowed to push out the project's final deadline.

    Leveling can change the critical path and project end date, whereas Smoothing only uses available float.

    Leveling prioritizes resource constraints over time, while Smoothing attempts to even out resource use without delaying the project finish.

    • ✗ Leveling is done manually, while Smoothing is always automated.

      Both can be performed manually or with software; the difference lies in their impact on the schedule baseline.

    • ✗ Smoothing is used for critical path activities, while Leveling is for non-critical activities.

      Both techniques can apply to any activity, but their constraints regarding the end date differ.

    • ✗ Leveling increases project cost, while Smoothing reduces project risk.

      While costs and risks may be affected, these are secondary outcomes compared to their primary definitions involving dates and float.

16. 16 A scheduler adds a $-3$ day modification to a Finish-to-Start relationship between two activities. This modification is technically known as a:

    Think about the term used for overlapping tasks to finish the project earlier.

    Lead

    A lead is an acceleration of the successor activity, often modeled as a negative lag in scheduling software.

    • ✗ Lag

      A lag is a positive value representing a required delay between activities.

    • ✗ Buffer

      A buffer is a reserve of time, usually placed at the end of a path, rather than a specific relationship acceleration.

    • ✗ Slack

      Slack, or float, is a calculated property of an activity, not a manual modification of a relationship.

17. 17 According to the Practice Standard for Scheduling, why should 'lags' not be used to represent time for document review?

    Consider the difference between a task that requires an owner and a physical waiting period.

    It hides work and responsibility, making it difficult to control the project if the reviewer is late.

    Lags should only represent physical delays (like concrete curing); actual work like reviews should be discrete activities for better visibility.

    • ✗ Lags automatically increase the standard deviation of the project finish date.

      While lags introduce risk, they do not inherently change the mathematical standard deviation unless specifically modeled that way.

    • ✗ Lags cannot be linked to resource calendars.

      Many software tools allow lag calculations to be calendar-dependent, but the issue is one of project visibility and control.

    • ✗ Document reviews are summary activities and cannot have predecessors.

      Reviews are discrete tasks that can and should have predecessors and successors in a logical network.

18. 18 An activity has a Late Start ($LS$) of Day $30$ and an Early Start ($ES$) of Day $22$. What is the Total Float?

    Find the difference between the earliest and latest possible start times.

    $8$ days

    Total Float is calculated as $LS - ES$ (or $LF - EF$), which in this case is $30 - 22 = 8$.

    • ✗ $52$ days

      This is the sum of the two dates, which has no meaning in critical path analysis.

    • ✗ $-8$ days

      A negative value would only occur if the Early Start was later than the Late Start, typically due to a constraint.

    • ✗ $0$ days

      Zero float only applies if the Early and Late dates are identical, meaning the activity is critical.

19. 19 In a Monte Carlo simulation, what does the 'Probability Density Function' of the project completion date help a scheduler understand?

    Think about how results of thousands of iterations are visualized to determine confidence levels.

    The likelihood of finishing the project on or before a specific date.

    Monte Carlo provides a range of possible dates and the statistical probability associated with each, allowing for risk-based commitments.

    • ✗ The exact cost required to crash the project by $10$ days.

      Crashing costs are typically deterministic inputs; Monte Carlo focuses on duration and probability.

    • ✗ Which specific resource is currently over-allocated.

      Resource over-allocation is identified through leveling and resource histograms, not probabilistic date simulations.

    • ✗ The logic error that caused an out-of-sequence condition.

      Logic errors are identified during network analysis and tool validation, not through simulation results.

20. 20 A scheduler is modeling 'Just-in-Time' (JIT) delivery for a construction project. Which modification is most likely to introduce a cascading risk if the site has limited storage?

    Consider the risk of finishing or starting something 'too early' when space is at a premium.

    Using Leads to bring materials to the site earlier than needed.

    Leads accelerate successors; if material arrives early in a JIT environment with no storage, it creates cost and logistical risks.

    • ✗ Applying a Lag to the start of the foundation work.

      Lags delay successors, which would delay material needs, potentially avoiding storage issues but delaying the project.

    • ✗ Using a Hammock activity to track the security team.

      Hammocks bridge other activities and do not directly impact material delivery or storage logic.

    • ✗ Setting a 'Finish-No-Later-Than' constraint on the project end date.

      Constraints impact float calculations but do not specifically model the risk of early inventory arrival.

21. 21 What is the primary purpose of a 'Forward Pass' in the Critical Path Method?

    Think about the first step in analyzing a logical network from its inception.

    To determine the early start and early finish dates for all activities.

    The forward pass moves through the network from start to finish to establish the earliest possible timing and the shortest overall duration.

    • ✗ To calculate the total float available for each task.

      Float cannot be calculated until both the forward and backward passes are complete.

    • ✗ To identify the late finish date constrained by the contract.

      Contractual constraints are inputs to the backward pass, which moves from the end of the project toward the beginning.

    • ✗ To resolve out-of-sequence work automatically.

      The forward pass only calculates dates based on existing logic; it does not correct logical errors or out-of-sequence issues.

22. 22 Which of the following is true regarding Level of Effort (LOE) activities in a schedule model?

    Recall that LOE work is supportive and its timing is dependent on other 'driving' tasks.

    They should generally not have constraints applied and should not be resource-leveled.

    LOEs take their duration from supported tasks; applying constraints or leveling them would interfere with this calculated relationship.

    • ✗ They are the primary drivers of the project's critical path.

      LOEs are supportive and should never drive the project duration or be critical tasks.

    • ✗ They must have a Finish-to-Start relationship with all deliverables.

      LOEs are typically modeled with SS and FF relationships to the activities they support.

    • ✗ Their duration is fixed during the planning phase and never changes.

      LOE durations are dynamic and fluctuate based on the duration of the work they support.

23. 23 If the Early Finish ($EF$) of an activity is Day $12$ and the Late Finish ($LF$) is Day $12$, what can be definitively concluded?

    Consider what it means when there is no difference between the earliest and latest finish times.

    The activity is on the critical path.

    When $EF = LF$ (or $ES = LS$), the Total Float is zero, which is the definition of a critical path activity.

    • ✗ The activity has a large amount of free float.

      If Total Float is zero, Free Float must also be zero, as Free Float cannot exceed Total Float.

    • ✗ The activity is a Level of Effort (LOE) task.

      Being critical or having zero float is a function of network logic, not the type of activity (LOE vs. Discrete).

    • ✗ The project is currently ahead of schedule.

      Float values indicate the plan's flexibility, not the current status of performance against that plan.

24. 24 A scheduler is performing 'Schedule Forensics' after a project delay. They are comparing the 'As-Built' schedule to the 'Baseline'. What is the 'Baseline' in this context?

    Identify the fixed reference point used to determine if a project is on track or delayed.

    The approved version of the schedule model used for performance measurement.

    The baseline is the static, approved reference point against which actual progress and changes are compared.

    • ✗ The current version of the schedule including all recent status updates.

      This describes the 'Current Schedule' or 'Statused Schedule,' which is dynamic and changes regularly.

    • ✗ A schedule model that assumes zero risk and unlimited resources.

      A realistic baseline must account for known constraints and risk to be valid for measurement.

    • ✗ The original project charter's high-level milestone list.

      The schedule baseline is a detailed model, much more granular than the high-level milestones in a charter.

25. 25 In the Precedence Diagramming Method, if a successor cannot finish until the predecessor has finished, the relationship is:

    Identify which specific milestones of the two tasks are being linked.

    Finish-to-Finish (FF)

    FF logic links the completion of one task to the completion of another.

    • ✗ Start-to-Finish (SF)

      SF links the 'start' of the predecessor to the 'finish' of the successor, which is rare.

    • ✗ Finish-to-Start (FS)

      FS links the 'finish' of the predecessor to the 'start' of the successor.

    • ✗ Start-to-Start (SS)

      SS links the 'start' of the predecessor to the 'start' of the successor.