Engineered Software

Continuous Distributions Practitioner's Exam

Weibull

Normal

Lognormal

Exponential

Engineered Software Home Page
  1. Given that a population of components has a normal time to fail distribution with a mean of 400 hours and a standard deviation of 60 hours, if 200 components are tested for 430 hours, what is the expected number of survivors?
    61.7
    31.7
    28.3
    None of the above
  2. Given that a population of components has a normal time to fail distribution with a mean of 400 hours and a standard deviation of 60 hours, if 200 components are tested for 430 hours, what is the expected number of failures between time = 410 and time = 430?
    14.24
    21.87
    25.05
    None of the above
  3. A population of components has a constant failure rate of 0.003 per hour. What is the probability of failure before 200 hours of operation?
    1
    0.387
    0.274
    None of the above
  4. The time to fail for a system follows the Weibull distribution with a shape parameter of 3.7 and a scale parameter of 89, what is the probability of failure before time = 80?
    0.487
    0.473
    0.463
    None of the above
  5. The time to fail for a system follows the Weibull distribution with a shape parameter of 0.7 and a scale parameter of 109, what is the probability of survival until = 80?
    0.2578
    0.4469
    0.6844
    None of the above
  6. The lognormal hazard function
    can be monotonically increasing
    can be monotonically decreasing
    both increases and decreases in all cases
    None of the above
  7. The Weibull hazard function
    can be monotonically increasing
    can be monotonically decreasing
    can be constant
    All of the above
  8. The lognormal distribution
    can be skewed left
    can be skewed right
    can have no skewness
    All of the above
  9. The Weibull distribution
    can be skewed left
    can be skewed right
    can have no skewness
    All of the above
  10. A component has a time to fail that is lognormally distributed with a shape parameter of 0.4 and a scale parameter of 2.  What is the reliability at time = 50?
    0
    1
    0.9993
    None of the above
  11. Which of the following is true?
    if two populations are compared, the population with the larger mean always has higher reliability
    if two populations are compared, the population with the larger mean always has higher variance
    if two populations are compared, the population with the larger mean always has higher survivability
    None of the above are true

BackHomeNext