FE Other Disciplines Practice Question Solution included after investigation
CASE E-095 Β· FE

The Process Choice That Broke Even at 10,000 Units, Not 5,000

The fixed-cost difference was correct, but break-even depends on the difference in variable costs. The correct crossover is 10,000 units.

β–Ά INTERACTIVE CASE FILE β€’ 5–10 MIN β€’ CLICK TO INVESTIGATE

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

Case E-095 engineering failure visual
HOW THIS WORKS

Think like
a real engineer.

Follow the investigation process used in the field β€” 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

Process A has fixed cost $80,000/year and variable cost $12/unit. Process B has fixed cost $140,000/year and variable cost $6/unit. Determine break-even quantity and the lower-cost option at 15,000 units/year.

Engineering Economics Other Disciplines Design Verification Root Cause Analysis Safe Correction
E-095
INVESTIGATION WORKSPACE WORK THROUGH THE CASE β€” YOUR CHOICES MATTER.
πŸ”’
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.

πŸ”’Root causeComplete the case
to reveal
πŸ”’Correct fixComplete the case
to reveal
πŸ”’Exam takeawayComplete the case
to reveal
CASE CLOSED Β· ENGINEERING VERDICT

What actually failed β€” and what should change.

What failed

Ξ”F was divided by one variable-cost rate.

What was missed

Both alternatives have variable costs.

Corrected model

Set F_A+v_AQ=F_B+v_BQ.

QUICK ANSWER

80,000+12Q=140,000+6Q gives Q=10,000 units/year. At 15,000 units, Process B costs $230,000 versus $260,000 for A.

ENGINEERING TAKEAWAY

Set total costs equal or divide the fixed-cost difference by the variable-cost difference.

CASE QUESTIONS

Questions this case should settle.

What is the break-even formula for two alternatives?

Q=(F2-F1)/(v1-v2), with consistent signs.

Which process is cheaper above break-even here?

Process B.

NEXT FE PRACTICE QUESTION

The Risky Project Worth $52,000, Not $35,000

Engineering Economics Β· 5–10 min

Continue Practice β†’
WHAT YOU’LL LEARN

Real failures. Lasting skills.

Each case is designed to build the judgment, analysis, and confidence you need for engineering exams β€” 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.