Lean Six Sigma Black Belt Certification Basic Lean Six Sigma Black Belt Certification 1 — Questions and Answers
Question 1: In a Six Sigma project, Defects Per Million Opportunities (DPMO) is calculated as which of the following?
- (Defects / Opportunities) × 1,000,000 (Correct answer)
- (Defects / Units) × 1,000,000
- (Defects × Opportunities) / Units
- (Units / Defects) × 1,000,000
Correct answer: (Defects / Opportunities) × 1,000,000
DPMO = (Number of Defects / Number of Opportunities) × 1,000,000. This normalizes the defect rate to a per-million scale, allowing comparison across processes with different opportunity counts.
Question 2: Which type of control chart is most appropriate for monitoring the proportion of defective items in subgroups of varying size?
- X-bar and R chart
- p-chart (Correct answer)
- c-chart
- I-MR chart
Correct answer: p-chart
The p-chart monitors the proportion (fraction) of defective units and accommodates varying subgroup sizes, making it the correct choice when sample sizes differ across inspection periods.
Question 3: In Design of Experiments (DOE), what is the purpose of replication?
- To reduce the number of experimental runs required
- To estimate experimental error and increase statistical power (Correct answer)
- To randomize the order of experimental runs
- To ensure all factors are tested at the same level
Correct answer: To estimate experimental error and increase statistical power
Replication involves running the same experimental conditions more than once. This allows estimation of pure experimental error and increases statistical power, making effects easier to detect reliably.
Question 4: In a Failure Mode and Effects Analysis (FMEA), the Risk Priority Number (RPN) is calculated as:
- Severity + Occurrence + Detection
- Severity × Occurrence × Detection (Correct answer)
- Severity × Occurrence / Detection
- (Severity + Detection) × Occurrence
Correct answer: Severity × Occurrence × Detection
RPN = Severity × Occurrence × Detection. Each factor is rated on a scale (typically 1–10) and multiplied together to prioritize failure modes that require corrective action.
Question 5: Which Lean tool is used to create a visual representation of the flow of materials and information required to bring a product from raw material to the customer?
- 5S methodology
- Kanban board
- Value Stream Map (Correct answer)
- Spaghetti diagram
Correct answer: Value Stream Map
Value Stream Mapping (VSM) documents all steps — both value-added and non-value-added — in the flow of materials and information, making waste and improvement opportunities visible across the entire process.
Question 6: In hypothesis testing, a p-value of 0.03 with a significance level (α) of 0.05 leads to which conclusion?
- Fail to reject the null hypothesis because p > α
- Reject the null hypothesis because p < α (Correct answer)
- Accept the null hypothesis because the difference is small
- Increase the sample size before drawing any conclusion
Correct answer: Reject the null hypothesis because p < α
When the p-value (0.03) is less than the significance level α (0.05), there is sufficient evidence to reject the null hypothesis. The result is statistically significant at the chosen α level.
Lean Six Sigma Black Belt Certification Basic Lean Six Sigma Black Belt Certification 1
In a Six Sigma project, Defects Per Million Opportunities (DPMO) is calculated as which of the following?