FE Civil Practice Question Solution included after investigation
CASE E-107 · FE

The Schedule That Finished in 16 Days, Not 12

The shorter branch finished in 12 days, but project completion waited on the longer A-B-D-F path. The correct duration was 16 days.

▶ INTERACTIVE CASE FILE • 5–10 MIN • CLICK TO INVESTIGATE

Inspect, commit, prove, fix, and sign off.

Case E-107 engineering failure visual
HOW THIS WORKS

Think like
a real engineer.

Follow the investigation process used in the field — in five guided steps.

1

Inspect

Review the problem, diagram, and evidence.

2

Commit

Choose your hypothesis.

3

Prove

Run calculations and test your idea.

4

Fix

Select and validate a safe correction.

5

Sign Off

See the full debrief and key takeaways.

Case Brief

SAME PRINCIPLES. HIGHER STANDARDS.
PROBLEM STATEMENT

A project has activities: A=3 days; B=5 after A; C=4 after A; D=6 after B; E=3 after C; F=2 after both D and E. Determine project duration, critical path, and total float on the C-E branch.

Construction Engineering Civil Design Verification Root Cause Analysis Safe Correction
E-107
INVESTIGATION WORKSPACE WORK THROUGH THE CASE — YOUR CHOICES MATTER.
🔒
DEBRIEF (LOCKED)

Complete the investigation
to unlock the full debrief.

Find the root cause, confirm the fix, and see how this connects to the exam.

🔒Root causeComplete the case
to reveal
🔒Correct fixComplete the case
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🔒Exam takeawayComplete the case
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CASE CLOSED · ENGINEERING VERDICT

What actually failed — and what should change.

What failed

The shorter parallel branch was treated as project duration.

What was missed

The merge activity waits for all predecessors.

Corrected model

Use forward/backward passes and identify the zero-float critical path.

QUICK ANSWER

A-B-D-F takes 3+5+6+2=16 days. A-C-E-F takes 12 days, so the project duration is 16 days and the shorter branch has 4 days of float.

ENGINEERING TAKEAWAY

Perform a forward pass and use the longest zero-float path as the project duration.

CASE QUESTIONS

Questions this case should settle.

What determines project duration in CPM?

The longest zero-float path through the activity network.

NEXT FE PRACTICE QUESTION

The Slab Order That Needed 80 yd³, Not 74.1

Construction Engineering · 5–10 min

Continue Practice →
WHAT YOU’LL LEARN

Real failures. Lasting skills.

Each case is designed to build the judgment, analysis, and confidence you need for engineering exams — and beyond.

  • Apply core engineering concepts to real-world problems
  • Practice structured troubleshooting and analysis
  • Strengthen exam-ready thinking through realistic scenarios
COMMON QUESTIONS
Do I need prior knowledge to use these cases?

Basic subject familiarity helps, but every case is designed to teach through the investigation itself.

How long does a case take?

Most cases are designed for a focused 5–10 minute investigation.

Are the cases aligned with engineering exams?

Each case is mapped to a verified exam, subject, topic, and misconception before publication.

What happens after I complete a case?

The sealed debrief unlocks with the root cause, corrected reasoning, fix, and takeaway.