Which of the following considerations should a criticality analysis (CA) take into account?
I. Consequences of a failure.
II. Consequential damage of a failure.
III. Damage to the environment.
IV. Potential increase in efficiencies.
Response:

• A.I and II only
• B.I only
• C.I, II, III and IV
• D.I, II and III only

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With respect to calculating a mission reliability, the time of the operating mission is:
Response:

• A.Important only when assuming a constant failure rate.
• B.Important only when discussing outer space exploration projects.
• C.More important than the failure rate.
• D.Always an important consideration.

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Which of the following is best defined as the practice of using parallel components and subsystems?
Response:

• A.Maintainability
• B.Optimization
• C.Reliability
• D.Redundancy

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Preventive maintenance is characterized by:
I. Replacing failed/defect items as they are found in normal service use II. A planned program of tests, inspections, and/or replacements III. Replacing items just before they fail Response:

• A.I only
• B.I and III only
• C.II only
• D.I, II and III

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Three identical subsystem are connected in an active parallel, non-load-sharing system. At least two of the tree must work in order for the system to work. The time to failure for each subsystem is exponential with a common failure rate, λ. The reliability of the system can be expressed as which of the following?
Response:

• A.1 -2 e - 3 λt - 3e - 2 λt
• B.3 e - 3 λt - 2e - 2 λt
• C.3 e - 2 λt - 2e - 3 λt
• D.1 -3 e - 2 λt + 2e - 2 λt

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