Free Certified Reliability Engineer (CRE) examination Practice Questions

Sample Practice Questions

Try these 10 sample questions from the Certified Reliability Engineer (CRE) examination practice bank. Each includes the answer and explanation. Continue with the interactive practice above to review the full question set.

1. 1A reliability engineer discovers that a failure summary omitted several valid failures because they made a prototype look unfavorable. What should the engineer do when preparing the report for a design decision?

   1. A. Retain the omissions and label the report a preliminary estimate.
   2. B. Restore the valid failures and disclose the basis of the analysis.
   3. C. Replace the omitted failures with the design team's target values.
   4. D. Report only the failures that support the proposed design choice.

   Answer: B

   Explanation: The ASQ Code calls for conduct that is "truthful and transparent". Restoring valid failures and explaining the analysis basis meets that expectation; preliminary status does not justify selective omission or replacement by targets.

   Reference: ASQ Code of Ethics — Expectations of a Quality Professional

2. 2Which set of questions provides the core of probabilistic risk assessment as described by the NRC?

   1. A. What failed, what repairs were completed, and how long did restoration take?
   2. B. What is the worst outcome, what loss is conceivable, and what harm is imaginable?
   3. C. How often is failure expected, how long until failure, and how many failures are expected?
   4. D. What can go wrong, how likely is it, and what are its consequences?

   Answer: D

   Explanation: The source states: "(1) what can go wrong, (2) how likely it is, and (3) what its consequences might be.". Repair history, consequences alone and frequency measures alone each omit essential parts of the scenario-likelihood-consequence triplet.

   Reference: NRC Glossary — Probabilistic Risk Assessment (PRA) — Glossary definition, Probabilistic risk assessment (PRA)

3. 3Independent events A and B have probabilities 0.02 and 0.03 during the same mission. What is the probability that both occur?

   1. A. 0.0500
   2. B. 0.0100
   3. C. 0.0006
   4. D. 0.0494

   Answer: C

   Explanation: The NASA handbook gives the independent-event rule: "P(A and B) = P(A) P(B)." Hence 0.02×0.03=0.0006. Addition gives an upper-bound sum, and the union calculation answers a different question.

   Reference: NASA Fault Tree Handbook with Aerospace Applications — Appendix B.4, Equation B.9, p. 172

4. 4Before selecting the unit count and duration for a reliability assessment test, which planning approach should the team use?

   1. A. Set sample size from chamber capacity alone, without specifying a statistical objective.
   2. B. Establish model assumptions, intended conclusions, and acceptable decision risks.
   3. C. Select the model only after choosing which test outcomes should count as acceptable.
   4. D. Set duration from an optimistic reliability estimate without selecting decision risks.

   Answer: B

   Explanation: The source states: "stating your assumptions and what you want to discover or prove". Assumptions, intended conclusions and decision risks establish the statistical purpose before resources determine a feasible plan. Capacity alone, outcome-driven choices or optimistic duration omit that basis.

   Reference: NIST/SEMATECH e-Handbook — Planning a Reliability Assessment Test — 8.3.1, opening planning guidance

5. 5An engineering test shows that a finished product satisfies each applicable technical requirement. Which design-evaluation purpose has this evidence directly addressed?

   1. A. Product verification
   2. B. Product validation
   3. C. Requirements definition
   4. D. Design trade-study evaluation

   Answer: A

   Explanation: The source states: "Verification of a product shows proof of compliance with requirements". Demonstrated compliance with technical requirements is product verification. Validation asks about stakeholder purpose; defining requirements and comparing design alternatives precede proof of product compliance.

   Reference: NASA Systems Engineering Handbook — Fundamentals of Systems Engineering — 2.4, Product Verification and Product Validation

6. 6An engineer is asked to independently approve a specialized reliability analysis that falls outside the engineer's training and expertise. Which response follows the ASQ Code of Ethics?

   1. A. Approve the analysis if its conclusion agrees with a previous project.
   2. B. Approve the analysis after adding a general limitation to the signature.
   3. C. Limit the assignment to competent work and seek qualified expertise.
   4. D. Accept the approval role because professional certification covers it.

   Answer: C

   Explanation: ASQ restricts assignments to "areas of competence". An engineer lacking the required specialized expertise should obtain qualified support or limit the role appropriately; a disclaimer, previous agreement or certification alone does not supply competence.

   Reference: ASQ Code of Ethics — Expectations of a Quality Professional

7. 7A cyber-risk assessment classifies likelihood using defined labels such as low, moderate, and high, without numerical values. How does NIST SP 800-30 characterize this approach?

   1. A. Qualitative, because it uses nonnumerical categories or levels
   2. B. Quantitative, because every category represents an exact probability
   3. C. Semi-quantitative, because no category definitions are needed
   4. D. Quantitative, because the categories preserve numerical proportionality

   Answer: A

   Explanation: NIST describes qualitative assessments as based on "nonnumerical categories or levels (e.g., very low, low, moderate, high, very high)." Labels are not exact probabilities or ratio-scaled measurements.

   Reference: NIST SP 800-30 Revision 1 — Guide for Conducting Risk Assessments — 2.3.2, Assessment Approaches, pp. 14–15

8. 8Two mutually exclusive failure categories have probabilities 0.12 and 0.08. What is the probability of observing either category?

   1. A. 0.20
   2. B. 0.04
   3. C. 0.0096
   4. D. 0.1904

   Answer: A

   Explanation: For mutually exclusive events, NASA gives: "P(A or B) = P(A) + P(B)." The categories cannot occur together, so 0.12+0.08=0.20. Subtracting an independent-event product would impose an incorrect overlap.

   Reference: NASA Fault Tree Handbook with Aerospace Applications — Appendix B.4, Equation B.3, p. 171

9. 9For the same MTBF objective and confidence level in an exponential acceptance test, how does allowing more failures affect the required test duration?

   1. A. It reduces duration because each failure provides acceptance credit.
   2. B. It leaves duration unchanged because only the MTBF objective matters.
   3. C. It increases duration while reducing rejection from random bad luck.
   4. D. It makes test duration irrelevant once any failure has occurred.

   Answer: C

   Explanation: NIST states: "The more fails allowed, the longer the test required." It explains that the longer plan reduces the chance that acceptable equipment is rejected because of random bad luck. Failure allowance and exposure must be selected together.

   Reference: NIST/SEMATECH e-Handbook — Exponential or HPP Model Tests — 8.3.1.1, How Long Must You Test?

10. 10A device meets its written specification, but representative users cannot accomplish the intended task in the intended environment. Which evaluation objective has not been demonstrated?

    1. A. Verification that the measured values meet the written requirements
    2. B. Confirmation that the test report records the observed values
    3. C. Calculation of conformance against each documented specification
    4. D. Validation that the product fulfills the intended stakeholder purpose

    Answer: D

    Explanation: NASA states: "Validation of a product shows that the product accomplishes the intended purpose in the intended environment". Specification conformance can coexist with failure to meet actual user needs; that is the validation concern.

    Reference: NASA Systems Engineering Handbook — Fundamentals of Systems Engineering — 2.4, Product Verification and Product Validation