ASQ Certified Quality Inspector & Reliability Engineer 4 — Questions and Answers
Question 1: When constructing an X-bar and R chart with a subgroup size of 5, which constant is used to calculate the upper control limit for the R chart?
- A2
- D4 (Correct answer)
- D3
- B4
Correct answer: D4
UCL_R = D4 × R-bar, where D4 is the control chart constant for the upper range limit at n=5 (D4 = 2.114).
Question 2: Which document formally specifies the characteristics that a product must possess to be considered acceptable?
- Control plan
- Inspection report
- Product specification (Correct answer)
- Process FMEA
Correct answer: Product specification
A product specification defines all required characteristics, dimensions, materials, and performance requirements a product must meet.
Question 3: The Weibull distribution is widely used in reliability engineering because it can model:
- Only wear-out failures
- Only random failures
- All three phases of the bathtub curve depending on the shape parameter β (Correct answer)
- Only infant mortality failures
Correct answer: All three phases of the bathtub curve depending on the shape parameter β
The Weibull shape parameter β < 1 models burn-in, β = 1 models random failures, and β > 1 models wear-out, making it extremely versatile.
Question 4: In a hypothesis test, a quality engineer sets α = 0.05. This means:
- There is a 5% chance the alternative hypothesis is true
- There is a 5% probability of rejecting the null hypothesis when it is actually true (Correct answer)
- 95% of the data falls within specification
- The test has 95% power
Correct answer: There is a 5% probability of rejecting the null hypothesis when it is actually true
The significance level α is the probability of a Type I error — concluding a difference exists when the null hypothesis is actually true.
Question 5: A quality inspector uses GO/NO-GO gauges primarily to:
- Measure the exact dimension of a part
- Determine surface roughness
- Verify a part conforms to upper and lower specification limits (Correct answer)
- Calculate process capability
Correct answer: Verify a part conforms to upper and lower specification limits
GO/NO-GO gauges quickly verify whether a feature falls within its tolerance limits without providing a variable measurement.
Question 6: Mean Time To Repair (MTTR) is a key metric of which reliability-related concept?
- Reliability
- Maintainability (Correct answer)
- Availability
- Durability
Correct answer: Maintainability
Maintainability is measured by MTTR — the average time required to restore a failed system to operational status.
Question 7: Which corrective action tool requires teams to identify all potential root causes of a problem using categories such as Machine, Method, Material, Man, Environment, and Measurement?
- Fault Tree Analysis
- Cause-and-Effect (Ishikawa) Diagram (Correct answer)
- 5 Whys
- Scatter Diagram
Correct answer: Cause-and-Effect (Ishikawa) Diagram
The Ishikawa (fishbone) diagram organizes potential causes into the 6M categories to systematically identify root causes.
ASQ Certified Quality Inspector & Reliability Engineer 4
When constructing an X-bar and R chart with a subgroup size of 5, which constant is used to calculate the upper control limit for the R chart?