Certified Six Sigma Black Belt Exam Practice 2 — Questions and Answers
Question 1: A Black Belt is analyzing a process with a mean of 50 and standard deviation of 5. If the USL is 65 and LSL is 35, what is the process Cpk?
- 1.00 (Correct answer)
- 1.33
- 0.67
- 2.00
Correct answer: 1.00
Cpk = min((USL-mean)/3σ, (mean-LSL)/3σ) = min(15/15, 15/15) = 1.00.
Question 2: During a DMAIC project, a team discovers that a key input variable accounts for 78% of output variation. This finding most likely comes from which tool?
- Pareto chart
- Regression analysis (Correct answer)
- Control chart
- FMEA
Correct answer: Regression analysis
Regression analysis quantifies the proportion of variance in the output explained by input variables (R²).
Question 3: A process produces 3.4 defects per million opportunities. This corresponds to which sigma level?
- 4σ
- 5σ
- 6σ (Correct answer)
- 3σ
Correct answer: 6σ
Six Sigma quality is defined as 3.4 DPMO, accounting for a 1.5σ long-term shift.
Question 4: Which type of hypothesis test would you use to compare the means of three or more independent groups simultaneously?
- Paired t-test
- Chi-square test
- One-way ANOVA (Correct answer)
- Two-sample t-test
Correct answer: One-way ANOVA
One-way ANOVA tests whether the means of three or more groups are statistically equal.
Question 5: In a full factorial DOE with 3 factors each at 2 levels, how many experimental runs are required (without replication)?
- 6
- 8 (Correct answer)
- 9
- 12
Correct answer: 8
A 2³ full factorial design requires 2³ = 8 runs.
Question 6: A control chart shows a run of 8 consecutive points on one side of the center line. This indicates:
- Normal process variation
- A special cause signal (Correct answer)
- Measurement system error
- Cpk below 1.0
Correct answer: A special cause signal
Eight consecutive points on the same side of the centerline is a standard Western Electric rule for a special cause signal.
Question 7: Which lean tool is used to visually distinguish normal from abnormal conditions in a workplace at a glance?
- 5S
- Visual management (Correct answer)
- Poka-yoke
- Kanban
Correct answer: Visual management
Visual management uses displays, color-coding, and markings so abnormal conditions are immediately obvious.
Certified Six Sigma Black Belt Exam Practice 2
A Black Belt is analyzing a process with a mean of 50 and standard deviation of 5.
If the USL is 65 and LSL is 35, what is the process Cpk?