CRE Statistical Methods and Reliability Modeling Flashcards
6 cards from real CRE practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 CRE Statistical Methods and Reliability Modeling flashcards as text
Which probability distribution is most commonly used to model the time between failures for electronic components during their useful life period?
Answer: Exponential distribution
During the useful life phase, the exponential distribution is used because it assumes a constant failure rate (λ).
A Weibull shape parameter (β) equal to 1 indicates which type of failure behavior?
Answer: Constant failure rate (random failures)
When β = 1, the Weibull distribution reduces to the exponential distribution, indicating a constant failure rate.
Mean Time Between Failures (MTBF) is mathematically the reciprocal of which reliability parameter?
Answer: Failure rate λ
MTBF = 1/λ, where λ is the constant failure rate under the exponential distribution assumption.
A component has an MTBF of 500 hours. What is its reliability at t = 500 hours assuming an exponential distribution?
Answer: 36.8%
R(t) = e^(-t/MTBF) = e^(-500/500) = e^(-1) ≈ 0.368 or 36.8%.
Which reliability system model assumes that the system fails when any single component fails?
Answer: Series system
In a series reliability model, all components must function for the system to function, so failure of any one causes system failure.
A Weibull shape parameter β < 1 is associated with which failure pattern in the bathtub curve?
Answer: Infant mortality (decreasing failure rate)
β < 1 indicates a decreasing hazard rate, corresponding to early-life or infant mortality failures.