BMAT Quality Control & Assurance 4 — Questions and Answers
Question 1: Which sampling strategy collects every nth item from a production run, offering simplicity while assuming the population is randomly ordered?
- Stratified sampling
- Cluster sampling
- Systematic sampling (Correct answer)
- Judgment sampling
Correct answer: Systematic sampling
Systematic sampling selects items at fixed intervals (every nth unit), but may introduce bias if the process has a cyclic pattern matching the interval.
Question 2: Under ISO 9001:2015, what is the purpose of an internal audit?
- To certify the organization's QMS for customer approval
- To determine whether the QMS conforms to requirements and is effectively implemented (Correct answer)
- To identify suppliers who do not meet quality standards
- To replace the management review process
Correct answer: To determine whether the QMS conforms to requirements and is effectively implemented
Internal audits verify that the QMS conforms to the organization's own requirements and the ISO standard, and that it is effectively maintained.
Question 3: The '5 Whys' technique is most appropriate for:
- Quantifying the financial impact of a quality problem
- Drilling down to the root cause of a problem through iterative questioning (Correct answer)
- Benchmarking against competitor quality levels
- Prioritizing multiple quality issues by frequency
Correct answer: Drilling down to the root cause of a problem through iterative questioning
The 5 Whys involves repeatedly asking 'why' (typically five times) until the fundamental root cause of a problem is uncovered.
Question 4: A process produces outputs with a mean of 50.2 mm and a standard deviation of 0.3 mm. The specification is 50 ± 1 mm. What is the approximate Cp value?
- 0.56
- 1.11 (Correct answer)
- 2.22
- 0.83
Correct answer: 1.11
Cp = (USL – LSL) / (6σ) = (51 – 49) / (6 × 0.3) = 2 / 1.8 ≈ 1.11, indicating the process spread fits within specs but centering should also be evaluated.
Question 5: Which document defines the quality requirements that a product or service must meet and forms the basis for acceptance criteria?
- Quality manual
- Work instruction
- Quality plan
- Product specification (Correct answer)
Correct answer: Product specification
A product specification defines the measurable requirements (dimensions, performance, material properties) against which the product is inspected and accepted or rejected.
Question 6: In statistical process control (SPC), a 'special cause' of variation is best described as:
- Inherent random variation present in every process
- An unpredictable variation from a specific identifiable source (Correct answer)
- The normal variation between operators
- Background noise that cannot be eliminated
Correct answer: An unpredictable variation from a specific identifiable source
Special cause variation is non-random, assignable to a specific factor (e.g., equipment failure, raw material change), and requires investigation and corrective action.
Question 7: Which lean quality tool involves creating a visual representation of the flow of materials and information to identify waste and improvement opportunities?
- Value stream mapping (Correct answer)
- 5S
- Single-minute exchange of die (SMED)
- Total productive maintenance (TPM)
Correct answer: Value stream mapping
Value stream mapping diagrams the entire flow from raw material to customer delivery, making non-value-added steps (waste) visible for elimination.
BMAT Quality Control & Assurance 4
Which sampling strategy collects every nth item from a production run, offering simplicity while assuming the population is randomly ordered?