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AACE CST practice questions

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Question 1Schedule Planning

Which schedule element marks a significant point in time and normally carries zero duration and no resources?

  1. A level-of-effort activity
  2. A milestone Correct answer.
  3. A hammock activity
  4. A summary bar

Explanation

A milestone is a zero-duration event used to mark a contractual date, a key deliverable, or the start or finish of a major scope element. Because it consumes no time or resources, it acts as a logic anchor rather than a work item.

Question 2Schedule Planning

What does the critical path of a CPM network represent?

  1. The sequence of activities carrying the lowest installed cost
  2. The path with the greatest peak resource demand
  3. The longest logic path, which sets the shortest project duration Correct answer.
  4. The chain containing the largest count of activities overall

Explanation

The critical path is the longest total-duration path through the logic network, so it determines the earliest possible project finish. Activities on it have the least total float, usually zero once the schedule is calculated to the required finish date.

Question 3Schedule Planning

In a precedence diagram, a 5-day lag on a finish-to-start relationship means that:

  1. The successor must finish 5 days after the predecessor begins
  2. The successor cannot start until 5 days after the predecessor finishes Correct answer.
  3. The predecessor and successor overlap for 5 working days
  4. The successor may start 5 days before the predecessor finishes

Explanation

Lag is waiting time inserted in a relationship, so an FS relationship with a 5-day lag pushes the successor's early start five working days after the predecessor's early finish. Lag can represent cure time, inspection periods, or contractual notice.

Question 4Schedule Planning

Which relationship type states that a successor cannot begin until its predecessor has completely finished?

  1. Start-to-start
  2. Finish-to-finish
  3. Finish-to-start Correct answer.
  4. Start-to-finish

Explanation

Finish-to-start is the most common relationship, linking the completion of the predecessor to the start of the successor. Start-to-start and finish-to-finish allow overlapping work, while start-to-finish is rarely used.

Question 5Schedule Planning

In a work breakdown structure, the lowest-level deliverable that is scheduled and estimated is called the:

  1. Code of accounts
  2. Work package Correct answer.
  3. WBS dictionary
  4. Control account

Explanation

The work package is the lowest WBS level at which scope, duration, and cost can be reliably planned and controlled. Schedulers typically build activities inside work packages rather than above them.

Question 6Schedule Planning

Total float of an activity is best defined as:

  1. The time it can slip without delaying the project finish Correct answer.
  2. The allowance built into calendars for weather and holidays
  3. The delay allowed before any immediate successor is pushed
  4. The gap between budgeted and actual activity duration

Explanation

Total float is the difference between late and early dates for an activity, measured against the project finish date. Delaying an activity by less than its total float does not move the project completion, although it may move successors.

Question 7Schedule Planning

A Level 1 schedule is typically used to:

  1. Perform detailed CPM calculations for each work package
  2. Track procurement of individual bulk materials
  3. Report executive summary milestones to management Correct answer.
  4. Direct daily crew assignments on site

Explanation

Level 1 schedules are executive summary schedules built around key milestones and major phases for management reporting. Detail increases as schedules move to Levels 2, 3, and below, with detailed CPM logic residing in the lower levels.

Question 8Schedule Planning

Which element defines the days and shifts on which a specific resource, such as a crane crew, is available to work?

  1. The project default calendar
  2. The schedule basis memorandum
  3. A resource calendar Correct answer.
  4. The activity duration type

Explanation

A resource calendar defines the working periods and availability limits for a specific resource or crew. The project calendar sets general working days, but resource calendars override it where equipment or labor availability differs.

Question 9Schedule Planning

Activity B has one predecessor, A, linked finish-to-start with a 3-day lag. Activity A finishes at the end of day 10. On a standard five-day calendar with no holidays, B's early start is:

  1. Day 10
  2. Day 14 Correct answer.
  3. Day 11
  4. Day 13

Explanation

Early start equals the predecessor's early finish plus the lag plus one day, so 10 + 3 + 1 = day 14. The three lag days occupy days 11, 12, and 13.

Question 10Schedule Planning

An activity has an early start of day 12 and a late start of day 18. Its total float is:

  1. 14 days
  2. 2 days
  3. 6 days Correct answer.
  4. 8 days

Explanation

Total float is the late start minus the early start, which here is 18 - 12 = 6 days. The same result would be obtained from the late finish minus the early finish.

Question 11Schedule Planning

A start-no-earlier-than constraint is placed on an activity that currently has positive total float. The likely effect is to:

  1. Reduce float when the constraint date falls after the early start Correct answer.
  2. Guarantee negative float on the activity and its predecessors
  3. Increase total float by the number of days between the two dates
  4. Remove the activity from the driving logic path permanently

Explanation

A start-no-earlier-than constraint resets the activity's early start to the constraint date when that date is later than the calculated early start. Float equal to the difference is thereby consumed, and if the date passes the late start, negative float appears.

Question 12Schedule Planning

An activity has 8 days of total float and its only successor also has 8 days of total float, with no lag on the link. The activity's free float is:

  1. 0 days Correct answer.
  2. 8 days
  3. Cannot be determined
  4. 4 days

Explanation

With no lag, free float equals the activity's total float minus the successor's total float, so 8 - 8 = 0. Free float can never exceed total float, which rules out the larger answers.

Question 13Schedule Planning

Resource leveling most commonly produces which effect on a CPM schedule?

  1. It replaces the need for an approved baseline
  2. It normally shortens the project by removing idle time
  3. It leaves dates unchanged because it only moves cost
  4. It can lengthen the project by consuming float Correct answer.

Explanation

Leveling delays activities to resolve resource peaks or over-allocation, which consumes float and can create new critical paths that extend the finish date. Leveling within float does not change the project finish, but leveling beyond float does.

Question 14Schedule Planning

Two otherwise identical 10-day activities use different calendars: one a five-day workweek, the other a seven-day workweek. Which statement is correct?

  1. Calendar assignment does not affect finish dates in CPM
  2. The five-day activity finishes first because it has fewer work hours
  3. Both activities finish on the same calendar date
  4. The seven-day activity finishes first in calendar time Correct answer.

Explanation

Duration is expressed in workdays, so a 10-day activity on a seven-day calendar spans fewer calendar days than the same duration on a five-day calendar. Calendars therefore shift finish dates even when durations in workdays are identical.

Question 15Schedule Planning

The schedule basis memorandum primarily serves to:

  1. Replace the cost estimate with cost loading
  2. Record daily quantities installed by each crew
  3. Document assumptions, calendars, constraints and logic decisions Correct answer.
  4. Authorize payment of schedule-related change orders

Explanation

The basis memorandum captures the assumptions, calendars, constraints, software settings, and logic rationale behind the schedule. It allows reviewers and successors to understand why the schedule looks as it does and supports validation during reviews.

Question 16Schedule Planning

An activity with no predecessor in the network is called an open end because it:

  1. Has no successor activity linked to it
  2. Is linked only by start-to-start relationships
  3. Has no driving logic tying it to project start Correct answer.
  4. Has zero duration and no resources

Explanation

An open end with no predecessor is not driven by any logic, so it can float freely and distort the calculated critical path and float values. Schedulers close open ends by tying such activities to project start or to other activities.

Question 17Schedule Planning

When crashing a schedule to shorten the project duration, the scheduler should first select an activity that is:

  1. Already complete so that no rework is required
  2. On a path with the largest total float available
  3. Non-critical but staffed by the largest crew
  4. On the critical path and cheapest per day of time saved Correct answer.

Explanation

Crashing only shortens the project when applied to the critical path, and the best candidate gives the lowest cost per unit of time saved without creating a new critical path or quality risk. Non-critical activities cannot shorten the project until their float is exhausted.

Question 18Schedule Planning

An activity shows 40 percent complete by duration but only 20 percent of its installed quantity in place. This most likely means:

  1. Physical progress lags elapsed time, so completion may slip Correct answer.
  2. The crew is performing ahead of planned productivity
  3. Duration-based percent complete is always the more accurate measure
  4. The activity should be removed from the critical path

Explanation

Quantity-based progress is a physical measure, so a 20 percent quantity against 40 percent elapsed duration signals productivity below plan. If the trend continues, the activity will need more time than scheduled unless performance improves.

Question 19Schedule Planning

Comparing the current schedule with the approved baseline is most valuable for:

  1. Computing earned value for completed work packages
  2. Assigning resources to newly added activities
  3. Identifying variances and supporting time extension requests Correct answer.
  4. Validating the logic links between detailed activities

Explanation

Baseline comparison shows how forecast dates and milestones have moved since approval, which supports variance reporting and delay analysis. It is the foundation for demonstrating the impact of changes and supporting extension-of-time claims.

Question 20Schedule Planning

A key advantage of a time-scaled logic diagram over a plain network diagram is that it:

  1. Removes the requirement for a data date
  2. Eliminates the need to calculate float values
  3. Shows float and logic against a calendar scale Correct answer.
  4. Allows activities to be drawn without durations

Explanation

A time-scaled logic diagram plots activities along a calendar axis while retaining the logic links, so reviewers can see float, sequence, and duration visually. Plain network diagrams show logic but not the position of activities in time.

Question 21Schedule Planning

A network has two paths to the finish: Path A at 20 days and Path B at 18 days. A 3-day lag is then added to a relationship on Path B only. The result is:

  1. Duration becomes 23 days because the lag applies to both paths
  2. Duration becomes 21 days and Path A gains one day of float Correct answer.
  3. Duration stays at 20 days because Path A is unchanged
  4. Path B stays non-critical because lags do not change path length

Explanation

Lag adds time to the path on which it is placed, so Path B grows to 21 days and becomes the new critical path. Path A, still at 20 days, now carries one day of total float.

Question 22Schedule Planning

Activity X has 6 days of total float and 2 days of free float. It is delayed 4 days with no other changes. The outcome is:

  1. Activity X becomes critical and its total float rises to 10 days
  2. No successor is affected and the activity's float is unchanged
  3. The project finish date slips by four working days
  4. Successors start 2 days later but the project finish is unchanged Correct answer.

Explanation

The delay exceeds free float by 2 days, so the immediate successors are pushed by 2 days, but the delay is within total float, so the project finish does not move. Total float drops from 6 to 2 days.

Question 23Schedule Planning

A scheduler must model 10 days of schedule contingency for a project. The preferred practice is to:

  1. Add a discrete contingency activity or buffer in the logic Correct answer.
  2. Move the data date back ten working days
  3. Add 10 days to each activity on the critical path
  4. Lengthen the project calendar by two working weeks

Explanation

Discrete contingency activities or buffers keep the allowance visible, identifiable, and removable once risk is retired. Padding durations or calendars hides the allowance and corrupts duration and productivity data.

Question 24Schedule Planning

When activities in a network are assigned different calendars, the critical path is:

  1. Unaffected by calendar differences because CPM counts workdays
  2. Always the path with the greatest number of activities
  3. The path with the longest calendar-adjusted duration Correct answer.
  4. The path with the greatest total number of work hours

Explanation

With mixed calendars, early and late dates are calculated in calendar time, so the driving path is the one with the longest calendar duration rather than the longest workday total. A path with fewer workdays on a restrictive calendar can therefore drive the project.

Question 25Schedule Planning

A critical-path activity with zero total float is delayed 5 days by a change order. What is the correct scheduling response?

  1. Shorten the baseline by 5 days to preserve the original finish
  2. Advance the data date and leave the network logic unchanged
  3. Update logic and durations, then recalculate to find the new critical path Correct answer.
  4. Take 5 days of float from non-critical activities to offset it

Explanation

Any delay to a critical activity shifts the forecast finish, so the schedule must be updated to reflect the change and recalculated to reveal the new critical path and float values. Recalculation also shows whether other paths have become driving.

Question 26Schedule Planning

At the lowest level of a work breakdown structure, the element that can be assigned to one responsible person and scheduled with defined start and finish dates is called a:

  1. Work package Correct answer.
  2. Project phase
  3. Deliverable
  4. Control account

Explanation

A work package is the lowest-level WBS element and is the natural building block for schedule activities because it can be assigned, estimated, and controlled. Control accounts sit above work packages and aggregate them for management purposes.

Question 27Schedule Planning

Which schedule component marks a significant point in time and has zero duration?

  1. Milestone Correct answer.
  2. Hammock activity
  3. Level-of-effort activity
  4. Summary activity

Explanation

A milestone is a zero-duration event used to mark a contract, approval, or key accomplishment. It consumes no time and therefore does not by itself affect the critical path.

Question 28Schedule Planning

In a precedence diagram, a lag is best described as:

  1. The duration of the predecessor activity
  2. A calendar constraint applied to the successor
  3. A mandatory waiting period between a predecessor and its successor Correct answer.
  4. The float available to the successor activity

Explanation

A lag is a specified time interval inserted into a logical relationship, such as a 3-day wait after a finish-to-start link. It models real waiting, curing, or review time and becomes part of the relationship logic.

Question 29Schedule Planning

An approved version of the project schedule used to compare progress and evaluate changes is called the:

  1. As-built schedule
  2. Target schedule
  3. Forecast schedule
  4. Baseline schedule Correct answer.

Explanation

The baseline is the approved reference schedule against which actual and forecast performance are measured. Changes to it normally require formal change control.

Question 30Schedule Planning

Activity A has an early start of day 5 and a duration of 4 days. Activity B has an early start of day 7 and a duration of 3 days. Both are finish-to-start predecessors of Activity C with no lag. What is the early start of Activity C?

  1. Day 10 Correct answer.
  2. Day 11
  3. Day 12
  4. Day 9

Explanation

The early finish of A is day 9 and of B is day 10. A finish-to-start successor cannot start until all predecessors finish, so C starts on day 10.

Question 31Schedule Planning

An activity has a late finish of day 30, a duration of 6 days, and an early finish of day 22. What is its total float?

  1. 8 days Correct answer.
  2. 7 days
  3. 6 days
  4. 9 days

Explanation

Total float equals late finish minus early finish, or 30 minus 22, which is 8 days. Equivalently, late start is 24 and early start is 16, giving the same result.

Question 32Schedule Planning

Activity B is linked to Activity A by a start-to-start relationship with a 4-day lag. Activity A starts on day 3. What is the earliest start of Activity B?

  1. Day 4
  2. Day 11
  3. Day 7 Correct answer.
  4. Day 3

Explanation

Under a start-to-start relationship, the successor cannot start until the predecessor has started plus the lag. Therefore B's early start is 3 + 4 = 7.

Question 33Schedule Planning

A resource histogram shows demand exceeding the available resource limit during weeks 4 through 6. What does this most directly indicate?

  1. The calendars are not assigned
  2. The cost baseline has been exceeded
  3. The critical path is invalid
  4. The schedule has resource over-allocation that may require leveling Correct answer.

Explanation

A histogram compares resource demand with availability over time; demand above the limit means over-allocation. The scheduler may need to level, shift, or adjust activities to keep demand within capacity.

Question 34Schedule Planning

Fast-tracking a schedule involves:

  1. Overlapping activities that were originally planned in sequence Correct answer.
  2. Reducing the project scope to meet a deadline
  3. Extending activity durations to absorb risk
  4. Adding resources to critical activities to shorten their durations

Explanation

Fast-tracking compresses duration by changing logic so sequential activities overlap, which can increase risk and rework. It does not add resources, cut scope, or extend durations.

Question 35Schedule Planning

Rolling wave planning is most appropriate when:

  1. No changes are expected for the entire project
  2. Detailed information is available only for near-term work Correct answer.
  3. The project is complete and being closed out
  4. The schedule has no critical path

Explanation

Rolling wave planning progressively elaborates the schedule as more information becomes available, so near-term work is detailed while far-term work remains at a higher level. It is common in projects with uncertainty or phased design.

Question 36Schedule Planning

Which practice most improves the reliability of a CPM schedule?

  1. Linking every activity to both a predecessor and a successor to eliminate open ends Correct answer.
  2. Assigning all activities to a single calendar
  3. Applying a date constraint to every activity
  4. Keeping every activity duration longer than 20 days

Explanation

Complete logic-every activity connected to at least one predecessor and successor except the project start and finish-allows the network to calculate float and criticality correctly. Open ends distort the critical path and float.

Question 37Schedule Planning

An activity is reported complete while its predecessor is still only 50 percent complete. This is best described as:

  1. Critical path compression
  2. Resource leveling
  3. Schedule contingency
  4. Out-of-sequence progress Correct answer.

Explanation

Out-of-sequence progress occurs when work is executed in an order that contradicts the network logic. The scheduler should resolve the logic or document the actual sequence so the update reflects reality.

Question 38Schedule Planning

A network has three paths to completion: Path 1 is 24 days, Path 2 is 21 days, and Path 3 is 19 days. A 6-day delay occurs on an activity that lies only on Path 2. What is the new project duration?

  1. 25 days
  2. 27 days Correct answer.
  3. 24 days
  4. 30 days

Explanation

Path 2 grows from 21 to 27 days, while Path 1 remains 24 days. Project duration is the longest path, so the new duration is 27 days.

Question 39Schedule Planning

Time impact analysis is used primarily to:

  1. Determine the schedule effect of a specific change or delay by inserting a fragnet into the current schedule Correct answer.
  2. Calculate earned value for completed work
  3. Approve the project baseline without change control
  4. Level resources across multiple projects

Explanation

Time impact analysis inserts a fragnet representing the change or delay into the current schedule at the correct point in time and measures the resulting effect on completion. It is a prospective method used in delay and change evaluation.

Question 40Schedule Planning

A deterministic CPM schedule shows 180 days to completion. A Monte Carlo simulation reports a P50 of 185 days and a P80 of 205 days. Which statement is correct?

  1. Completion will occur exactly on day 205 with 80 percent confidence
  2. The P50 value means the project has 50 days of float
  3. The deterministic duration of 180 days is the most likely outcome
  4. There is an 80 percent probability that completion will occur within 205 days Correct answer.

Explanation

In a cumulative probability distribution, P80 is the duration with an 80 percent chance of not being exceeded. It is not an exact completion date, and P50 is the median simulated duration, not float.

Question 41Schedule Development

What is the primary role of the work breakdown structure (WBS) in schedule development?

  1. Determine cost markup for each account
  2. Define activity sequence and logic ties
  3. Establish the contract payment terms that apply to each subcontractor
  4. Break project scope into manageable work packages Correct answer.

Explanation

The WBS hierarchically decomposes project scope into deliverables and work packages; schedule activities are then linked to those work packages so progress and responsibility align with scope. It is not a procurement or pricing tool, and network logic is developed after the work packages are identified.

Question 42Schedule Development

Which characteristic describes a milestone in a CPM schedule?

  1. It appears only in Level 1 summary schedules
  2. It must always lie on the critical path
  3. It has a duration equal to the duration of its longest predecessor
  4. It is a zero-duration event marking a significant point Correct answer.

Explanation

A milestone is a zero-duration marker of a significant event, decision, or deliverable; it consumes no time and usually has no resources. It may be critical, but that is not a defining requirement, and milestones appear at multiple schedule levels.

Question 43Schedule Development

In the critical path method, what does the critical path represent?

  1. The sequence with the lowest cumulative cost
  2. The longest path through the network Correct answer.
  3. The path with the greatest total float
  4. The path containing the most activities

Explanation

The critical path is the longest continuous path through the network when durations and calendars are applied. Its length establishes the shortest possible project duration, and activities on it normally have zero or minimum total float.

Question 44Schedule Development

A finish-to-start (FS) relationship between Activity A and Activity B means that:

  1. A and B must start on the same date
  2. A cannot finish until B starts
  3. B can finish only after A starts
  4. B cannot start until A finishes Correct answer.

Explanation

In a finish-to-start relationship, the successor's start is driven by the predecessor's finish, optionally adjusted by a lag. The other relationships shift the dependency to start-to-start or finish-to-finish logic.

Question 45Schedule Development

Total float of a schedule activity is the amount of time it can be delayed:

  1. Without changing its own duration
  2. Without affecting any direct predecessor
  3. Without delaying the project finish date Correct answer.
  4. Only if the activity is a milestone

Explanation

Total float is calculated as late finish minus early finish or late start minus early start. It measures how long an activity can slip before the project finish date or an imposed finish constraint is affected.

Question 46Schedule Development

What is the schedule baseline?

  1. Most recent update containing actual dates
  2. List of pending schedule changes awaiting approval
  3. First draft schedule produced before logic is added
  4. Approved schedule used to measure performance Correct answer.

Explanation

The schedule baseline is the approved, controlled version of the schedule used to compare actual and forecast performance. Updates may change the forecast, but the baseline changes only through formal change control.

Question 47Schedule Development

When activities in a schedule follow different working patterns, what is required for correct date calculations?

  1. Use milestone dates as the only calendar reference
  2. Apply a single 24-hour calendar to every activity in the schedule
  3. Assign an appropriate calendar to each activity or resource Correct answer.
  4. Remove every nonworking period from the project calendar

Explanation

CPM calculations depend on calendars because nonworking periods, shifts, and holidays determine when work can occur. When activities or resources follow different patterns, each must carry the calendar that represents its actual working time.

Question 48Schedule Development

Activity A finishes at the end of Tuesday. Its successor has a finish-to-start relationship with a 2-day lag. Assuming a Monday-through-Friday workweek, when can the successor start?

  1. Wednesday
  2. Thursday
  3. Monday of the following week
  4. Friday Correct answer.

Explanation

An FS lag adds working time after the predecessor finishes before the successor may start. With a Tuesday finish and a 2-day lag, Wednesday and Thursday are consumed, so the successor starts Friday.

Question 49Schedule Development

An activity has an earliest start of day 10 and duration of 5 days. Its latest finish is day 20. What is its total float?

  1. 5 days Correct answer.
  2. 0 days
  3. 15 days
  4. 10 days

Explanation

Earliest finish equals earliest start plus duration: 10 + 5 = 15. Total float equals latest finish minus earliest finish: 20 - 15 = 5 days.

Question 50Schedule Development

Which scheduling technique can extend the project finish date while resolving resource over-allocation?

  1. Crashing
  2. Resource smoothing
  3. Resource leveling Correct answer.
  4. Fast tracking

Explanation

Resource leveling resolves over-allocation by shifting or delaying activities, sometimes beyond available float, which can extend the project finish. Resource smoothing stays within existing float, while fast tracking and crashing are schedule compression techniques.