Six Sigma Black Belt Certification – 100 Practice
Questions with Answers & Rationales
1. Which of the following best describes the primary role of a Six
Sigma Black Belt within an organization?
A. To supervise operators during daily production tasks
B. To manage finances of improvement programs
C. To lead cross-functional project teams using advanced statistical
methods
D. To perform basic data collection only
Rationale: Black Belts are leaders of major improvement projects,
applying advanced tools and mentoring Green Belts.
2. Which phase of DMAIC focuses on identifying the root cause of
defects?
A. Define
B. Measure
C. Analyze
D. Control
Rationale: Analyze evaluates data to determine true root causes
driving the problem.
3. In Six Sigma, the term DPMO stands for:
A. Defects per manufacturing output
B. Defects per million opportunities
C. Defects per million operations
,D. Defects per manual observation
Rationale: DPMO quantifies expected defects per one million
opportunities for error.
4. A process with a Z-score of 4.5 corresponds to approximately what
sigma level?
A. 3.0
B. 4.0
C. 4.5
D. 6.0
Rationale: Process sigma is defined directly by its Z-score when long-
term shift is not applied.
5. Which of the following tools is typically used in the Define phase?
A. Regression analysis
B. Design of experiments
C. Hypothesis testing
D. SIPOC diagram
Rationale: SIPOC is used at project start to map suppliers, inputs,
process, outputs, and customers.
6. The Voice of the Customer (VOC) is used primarily to:
A. Train employees
B. Translate customer needs into measurable requirements
C. Estimate cost of poor quality
D. Validate control charts
,Rationale: VOC feeds CTQs by converting customer feedback into
quantifiable performance measures.
7. Which statistical test is appropriate to compare means of more
than two groups?
A. Chi-square test
B. ANOVA
C. F-test for variance
D. Mann-Whitney U test
Rationale: ANOVA compares mean differences across multiple groups.
8. A CTQ stands for:
A. Critical tool for quality
B. Critical to quality
C. Cost to quality
D. Capability to quantify
Rationale: CTQs specify measurable characteristics critical to customer
satisfaction.
9. Which chart is best for monitoring defects per unit?
A. X-bar chart
B. U-chart
C. S chart
D. Moving range chart
Rationale: U-charts handle varying opportunities and track defects per
unit.
, 10. A key output of the Measure phase is:
A. Root cause analysis
B. Baseline process capability
C. Future-state value stream map
D. Control plan
Rationale: Measure quantifies current performance to establish the
baseline for improvement.
11. The null hypothesis (H₀) in hypothesis testing typically states:
A. The claim the researcher wants to prove
B. There is no significant difference or effect
C. The effect is always present
D. The variance is always equal
Rationale: H₀ assumes no change; statistical testing tries to disprove
it.
12. A Pareto chart is used to:
A. Display normal distributions
B. Display process capability
C. Show the most significant contributors to a problem
D. Assess measurement system variation
Rationale: Pareto charts follow the 80/20 principle to prioritize issues.
13. Which DOE design evaluates multiple factors at two levels each?
A. Randomized block design
B. Full factorial design
C. Nested design
Questions with Answers & Rationales
1. Which of the following best describes the primary role of a Six
Sigma Black Belt within an organization?
A. To supervise operators during daily production tasks
B. To manage finances of improvement programs
C. To lead cross-functional project teams using advanced statistical
methods
D. To perform basic data collection only
Rationale: Black Belts are leaders of major improvement projects,
applying advanced tools and mentoring Green Belts.
2. Which phase of DMAIC focuses on identifying the root cause of
defects?
A. Define
B. Measure
C. Analyze
D. Control
Rationale: Analyze evaluates data to determine true root causes
driving the problem.
3. In Six Sigma, the term DPMO stands for:
A. Defects per manufacturing output
B. Defects per million opportunities
C. Defects per million operations
,D. Defects per manual observation
Rationale: DPMO quantifies expected defects per one million
opportunities for error.
4. A process with a Z-score of 4.5 corresponds to approximately what
sigma level?
A. 3.0
B. 4.0
C. 4.5
D. 6.0
Rationale: Process sigma is defined directly by its Z-score when long-
term shift is not applied.
5. Which of the following tools is typically used in the Define phase?
A. Regression analysis
B. Design of experiments
C. Hypothesis testing
D. SIPOC diagram
Rationale: SIPOC is used at project start to map suppliers, inputs,
process, outputs, and customers.
6. The Voice of the Customer (VOC) is used primarily to:
A. Train employees
B. Translate customer needs into measurable requirements
C. Estimate cost of poor quality
D. Validate control charts
,Rationale: VOC feeds CTQs by converting customer feedback into
quantifiable performance measures.
7. Which statistical test is appropriate to compare means of more
than two groups?
A. Chi-square test
B. ANOVA
C. F-test for variance
D. Mann-Whitney U test
Rationale: ANOVA compares mean differences across multiple groups.
8. A CTQ stands for:
A. Critical tool for quality
B. Critical to quality
C. Cost to quality
D. Capability to quantify
Rationale: CTQs specify measurable characteristics critical to customer
satisfaction.
9. Which chart is best for monitoring defects per unit?
A. X-bar chart
B. U-chart
C. S chart
D. Moving range chart
Rationale: U-charts handle varying opportunities and track defects per
unit.
, 10. A key output of the Measure phase is:
A. Root cause analysis
B. Baseline process capability
C. Future-state value stream map
D. Control plan
Rationale: Measure quantifies current performance to establish the
baseline for improvement.
11. The null hypothesis (H₀) in hypothesis testing typically states:
A. The claim the researcher wants to prove
B. There is no significant difference or effect
C. The effect is always present
D. The variance is always equal
Rationale: H₀ assumes no change; statistical testing tries to disprove
it.
12. A Pareto chart is used to:
A. Display normal distributions
B. Display process capability
C. Show the most significant contributors to a problem
D. Assess measurement system variation
Rationale: Pareto charts follow the 80/20 principle to prioritize issues.
13. Which DOE design evaluates multiple factors at two levels each?
A. Randomized block design
B. Full factorial design
C. Nested design
