FE Industrial & Systems Practice Question Solution included after investigation
CASE E-082 Β· FE

The Forecast That Moved to 109, Not 130

The latest actual demand was 130 units, but exponential smoothing with Ξ±=0.30 did not replace the forecast with 130. The next forecast became 109.

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

Case E-082 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

A production planner uses single exponential smoothing. The current-period forecast was 100 units, actual demand was 130 units, and Ξ±=0.30. A note sets the next-period forecast directly to 130 units. Determine the correct next-period forecast.

Manufacturing Service Production Systems Industrial Systems Design Verification Root Cause Analysis Safe Correction
E-082
INVESTIGATION WORKSPACE WORK THROUGH THE CASE β€” YOUR CHOICES MATTER.
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DEBRIEF (LOCKED)

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

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

What actually failed β€” and what should change.

What failed

The latest actual demand was copied directly into the next forecast.

What was missed

The previous forecast retains weight when Ξ± is less than one.

Corrected model

Use Fnext=Ξ±A+(1-Ξ±)F.

QUICK ANSWER

Using Fnext=Ξ±A+(1-Ξ±)F, the next forecast is 0.30(130)+0.70(100)=109 units.

ENGINEERING TAKEAWAY

Single exponential smoothing updates the forecast as Fnext=Ξ±Acurrent+(1-Ξ±)Fcurrent, so the new forecast is a weighted combination unless Ξ±=1.

CASE QUESTIONS

Questions this case should settle.

What is the single exponential smoothing formula?

Fnext=Ξ±Acurrent+(1-Ξ±)Fcurrent.

What happens when Ξ± increases?

The forecast responds more strongly to the latest actual observation.

NEXT FE PRACTICE QUESTION

The Inventory Policy That Ordered 707 Units, Not 10,000

Manufacturing Service Production Systems 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.