TECH SPOT: SAMPLE CRE QUESTIONS (Part 9)

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1. The effects of failure rates on increased temperatures is called the:

a. Thermal model

b.  Full scale Model 

c. Arrhenius Model  

d. Derating effects

2. Recognizing the nature of process variability, the process capability target is usually:

a. looser than product specifications     

b. the same as product specifications

c.  tighter than product specifications   

d. not related to product specifications

3. (blank)  software failure are the result of design errors.

a. All    b. Most    c. Many    d. No

4.  How can linear acceleration be verified?

a. with a probability plot  

b. with a hazard plot   

c. either a. or b. 

None of the above

5. The purpose of derating parts is to:

a. Increase parts life   

b. Enhance overall system reliability

c. Improve circuit design   

d. All of these

6.  A sequential test plan is graphically  shown in the figure below. If the first  3 items tested fail, and the next 18 succeed, what is the status of the test?

a.  Reject the null hypothesis 

b.  Accept the null hypothesis 

c. Continue testing     

d. None of these

7. Inherent of intrinsic reliability:

a. is that reliability which can only be improved by design change

b. can be improved only by an improvement in the state of the art

c. is that reliability estimated over stated period of time by a stated measurement technique.

d. is not an estimated reliability

8.An item has a constant failure rate of 50, and a constant repair rate of 22, what is the steady-state availability?

a.  0.983     b.  0.924   c. 0.815   d. none of the these

9.  The failure rate for a carpet manufacturer is 3.7 per 1000 square yards. What is the probability of finding no defects in  a  random sample of 100 square yards.

a. 0.7145    b. 0.6907    c. 0.9581     d. none of these        

10. Given a shape parameter of 1.7 for the Weibull distribution, and assuming no failures, how long will 20 items have to be tested to give  a reliability of  0.95 at t=100,000 with 90% confidence?

a. 119.329     b. 160,896    c. 189,744    d. 276,901

Picture © B. Poncelet https://bennyponcelet.wordpress.com

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