CRE CRE Statistical Methods and Reliability Modeling

Question 1

Which probability distribution is most commonly used to model the time between failures for electronic components during their useful life period?

Accepted Answer

Exponential distribution

Answer

Weibull distribution

Answer

Normal distribution

Answer

Lognormal distribution

Question 2

A Weibull shape parameter (β) equal to 1 indicates which type of failure behavior?

Accepted Answer

Constant failure rate (random failures)

Answer

Wear-out failures with increasing failure rate

Answer

Infant mortality with decreasing failure rate

Answer

Bathtub curve pattern

Question 3

Mean Time Between Failures (MTBF) is mathematically the reciprocal of which reliability parameter?

Accepted Answer

Failure rate λ

Answer

System reliability R(t)

Answer

Availability A

Answer

Maintainability M(t)

Question 4

A component has an MTBF of 500 hours. What is its reliability at t = 500 hours assuming an exponential distribution?

Accepted Answer

36.8%

Answer

50.0%

Answer

63.2%

Answer

100.0%

Question 5

Which reliability system model assumes that the system fails when any single component fails?

Accepted Answer

Series system

Answer

Parallel system

Answer

k-out-of-n system

Answer

Active standby system

Question 6

A Weibull shape parameter β < 1 is associated with which failure pattern in the bathtub curve?

Accepted Answer

Infant mortality (decreasing failure rate)

Answer

Wear-out failures

Answer

Constant random failures

Answer

Stress-related failures