Online Access Free CRE Practice Test

What is meant by reliability assurance?
I. The probability of performing a specified function without failure under given conditions for a specified period of time.
II. The exercise of positive and deliberate measures to provide confidence that a specified reliability will be obtained.
III. The probability that a product or component will be accepted by the customer.
Response:

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

When a bathtub curve is used, one characteristic of the flat center portion of the curve is that during this period Response:

• A.The reliability of the system can be expressed as an exponential function
• B.The equipment can be considered highly reliable.
• C.The time of the next failure is predictable from the time of the last failure.
• D.There can be only one type of failure in the system.

Probability ratio sequential tests are used for products designed to operate for a long period of time.
This test is primarily based on:
Response:

• A.Type I versus type II errors.
• B.The ratio of an acceptable MTBF to an unacceptable MTBF.
• C.Accept regions versus reject regions.
• D.Truncation of test results.

Which of the following is the MOST appropriate reason for selecting accelerated life testing for an expensive product to determine adherence to design requirements?
Response:

• A.The current sample size and the life distribution show wear-out is likely
• B.The test time to provide adequate reliability assurance under normal operating conditions is too long.
• C.The error in the population due to part-to-part variation is too large.
• D.The probability density function of the product follows either a log normal or a Weibull distribution.

Which of the following statement is TRUE about environmental stress screening (ESS)?
Response:

• A.It stresses equipment beyond design limits
• B.It is used to validate a design.
• C.It is a form of accelerated testing.
• D.It involves random sampling