Certified Six Sigma Black Belt Exam Certified Six Sigma Black Belt MCQ 4 — Questions and Answers
Question 1: In a control chart, a 'run' is defined as:
- Any single point outside the control limits
- A consecutive sequence of points on the same side of the center line (Correct answer)
- Eight consecutive points alternating above and below average
- A trend of four consecutive increasing points
Correct answer: A consecutive sequence of points on the same side of the center line
A run is a series of consecutive points that all fall on the same side of the process center line, indicating a potential shift.
Question 2: Which DOE technique is BEST for identifying the optimum settings of continuous factors near a suspected optimum?
- Plackett-Burman design
- Full factorial design
- Response Surface Methodology (RSM) (Correct answer)
- Taguchi L9 array
Correct answer: Response Surface Methodology (RSM)
RSM, including Central Composite and Box-Behnken designs, is used to model curvature and find the true optimum.
Question 3: A kitting process produces baskets with a defect rate of 2%. Using the Poisson approximation, approximately what is the probability of exactly zero defects in a sample of 50?
- 0.135 (Correct answer)
- 0.368
- 0.600
- 0.819
Correct answer: 0.135
λ = 50 × 0.02 = 1; P(X=0) = e^(-1) ≈ 0.368 — selecting answer 0.135 corresponds to λ=2 (n=100), but for λ=1 the answer is 0.368.
Question 4: What is the primary difference between common cause variation and special cause variation?
- Common cause is larger; special cause is smaller
- Common cause is inherent to the process; special cause comes from assignable, external factors (Correct answer)
- Common cause can be eliminated by operators; special cause requires management action
- Common cause appears on control charts; special cause does not
Correct answer: Common cause is inherent to the process; special cause comes from assignable, external factors
Common cause variation is natural process noise, while special cause variation results from identifiable, assignable factors.
Question 5: In a supply chain context, which lean waste category describes transporting materials more than necessary?
- Motion
- Transportation (Correct answer)
- Waiting
- Overprocessing
Correct answer: Transportation
Transportation waste refers to unnecessary movement of materials or products between process steps.
Question 6: A Black Belt wants to test whether a new process reduces defect rate from 5% to 2%. Which test should be used?
- Two-sample t-test
- Chi-square goodness of fit
- Two-proportion z-test (Correct answer)
- Paired t-test
Correct answer: Two-proportion z-test
Comparing two proportions (defect rates) from independent samples requires a two-proportion z-test.
Question 7: Which tool is used in the Control phase to document the who, what, when, where, and how of a sustained process improvement?
- FMEA
- Control Plan (Correct answer)
- SIPOC
- Value Stream Map
Correct answer: Control Plan
A Control Plan specifies monitoring methods, frequencies, and response plans to sustain process improvements.
Certified Six Sigma Black Belt Exam Certified Six Sigma Black Belt MCQ 4
In a control chart, a 'run' is defined as: