Lean Six Sigma Green Belt Certification Knowledge 3 — Questions and Answers
Question 1: A Green Belt calculates a process sigma level of 4.5. Approximately what is the defects per million opportunities (DPMO)?
- 3.4 DPMO
- 233 DPMO (Correct answer)
- 6,210 DPMO
- 66,807 DPMO
Correct answer: 233 DPMO
A process at 4.5 sigma corresponds to approximately 233 DPMO, well below the 6-sigma target of 3.4 DPMO.
Question 2: Which tool is used to prioritize potential failure modes by evaluating severity, occurrence, and detectability?
- Control chart
- FMEA (Correct answer)
- Value stream map
- Affinity diagram
Correct answer: FMEA
Failure Mode and Effects Analysis (FMEA) uses a Risk Priority Number (RPN = Severity × Occurrence × Detection) to rank and prioritize risks.
Question 3: In a value stream map, what does a 'push' arrow symbol indicate?
- Material flow pulled by customer demand
- Material pushed to the next step regardless of need (Correct answer)
- Electronic information flow
- Inventory supermarket location
Correct answer: Material pushed to the next step regardless of need
A push arrow shows that material is moved to the next process based on a schedule or batch, not on actual downstream demand.
Question 4: The Kano model classifies customer requirements into three main categories. Which category represents features customers expect as basic, causing dissatisfaction if absent?
- Performance needs
- Excitement needs
- Basic needs (Must-be) (Correct answer)
- Indifferent needs
Correct answer: Basic needs (Must-be)
Basic (Must-be) needs are taken for granted; their absence causes strong dissatisfaction, but their presence does not increase satisfaction.
Question 5: What does the term 'takt time' represent in Lean manufacturing?
- The time it takes to complete one unit from start to finish
- The rate of customer demand expressed as available time divided by demand (Correct answer)
- The time a product spends waiting in a queue
- The total processing time across all value-added steps
Correct answer: The rate of customer demand expressed as available time divided by demand
Takt time = available production time ÷ customer demand rate, setting the pace production must match to meet demand without overproduction.
Question 6: Which statistical test is most appropriate for comparing the means of two independent groups when data is normally distributed?
- Chi-square test
- Two-sample t-test (Correct answer)
- ANOVA
- Mann-Whitney U test
Correct answer: Two-sample t-test
The two-sample t-test compares means of two independent, normally distributed populations to determine if a statistically significant difference exists.
Question 7: A control chart shows a run of 8 consecutive points on one side of the centerline. This pattern indicates:
- Normal common cause variation
- A special cause requiring investigation (Correct answer)
- The process is out of specification
- The control limits need recalculation
Correct answer: A special cause requiring investigation
Eight or more consecutive points on one side of the centerline is a Western Electric rule violation signaling a special cause shift in the process mean.
Lean Six Sigma Green Belt Certification Knowledge 3
A Green Belt calculates a process sigma level of 4.5.
Approximately what is the defects per million opportunities (DPMO)?