CPT Quality Assurance & Process Control 3 — Questions and Answers
Question 1: On an X-bar and R chart, the R chart monitors:
- The process mean over time
- The variation within subgroups (Correct answer)
- The number of defects per unit
- The proportion of nonconforming items
Correct answer: The variation within subgroups
The R (range) chart tracks the spread or variability within each subgroup, measuring within-subgroup variation.
Question 2: Which quality cost category includes scrap, rework, and warranty repairs?
- Prevention costs
- Appraisal costs
- Internal failure costs (Correct answer)
- External failure costs
Correct answer: Internal failure costs
Scrap and rework are internal failure costs because they occur before the product reaches the customer; warranty repairs are external failure costs.
Question 3: A process produces 500 units with 15 defective. What is the defect rate expressed as a percentage?
- 1.5%
- 3.0% (Correct answer)
- 5.0%
- 7.5%
Correct answer: 3.0%
Defect rate = (15 ÷ 500) × 100 = 3.0%, calculated by dividing defectives by total units produced.
Question 4: The primary purpose of a gage R&R study is to:
- Determine if a process meets customer specifications
- Evaluate the measurement system's contribution to total variation (Correct answer)
- Calculate the process capability index
- Identify special causes of variation
Correct answer: Evaluate the measurement system's contribution to total variation
Gage R&R (Repeatability and Reproducibility) quantifies how much of the observed variation comes from the measurement system itself versus actual part variation.
Question 5: In Six Sigma, DMAIC stands for Define, Measure, Analyze, Improve, and:
- Implement
- Inspect
- Control (Correct answer)
- Correct
Correct answer: Control
Control is the final phase of DMAIC, focused on sustaining improvements and preventing the process from reverting to its previous state.
Question 6: Which chart is most appropriate for monitoring the number of defects on a single unit when the sample size is constant?
- p-chart
- np-chart
- c-chart (Correct answer)
- u-chart
Correct answer: c-chart
A c-chart monitors the count of defects per inspection unit when the sample size remains constant.
Question 7: ISO 9001 certification primarily demonstrates that an organization has:
- Zero defect production processes
- A documented and consistently followed quality management system (Correct answer)
- The lowest cost manufacturing in its industry
- Achieved Six Sigma performance levels
Correct answer: A documented and consistently followed quality management system
ISO 9001 certifies that a company has established and maintains a documented quality management system that consistently meets requirements.
CPT Quality Assurance & Process Control 3
On an X-bar and R chart, the R chart monitors: