# TECH SPOT: SAMPLE CRE QUESTIONS (Part 8)

1. Given the density function obtained under accelerated conditions: Determine the density function under normal operating conditions, given an acceleration factor of 5

** a. (1/150)exp(-t/150) **

b.(1/6)exp(-t/6)

c. (1/30)exp(-t/6)

d. (1/30)exp(-t/150)

2. Which of the following is NOT a type of sample?

a. acceptance sample

b. SPC sample

**c. Application sample **

d. Measurement system correlation sample

3. Failure rate derating curves are not dependent upon:

a. Environmental stresses

**b. Operating life **

c. Failures per hour

d. Component application levels

4. FMECA classifies each failure mode according to:

a. Probability

b. Criticality

**c. Severity **

d. Unreliability

5. Allocation of functions to personnel and equipment in combinations to achieve the required reliability is defined as

a. Human Factors allocation

b. Design Factors allocation

**c. The function allocation **

d. Cross-functional allocation

6. The reliability of the logic diagram is:

a. 0.1800 b. 0.5918 c. 0.7796 **d. 0.8201**

7. What does the failure mode and criticality number (C_{m}) replace in the most common qualitative methods?

a. Severity number

**b. Risk Priority number**

c. Failure Effects Number

d. Failure mode number

8. Two gages are used to inspect an item, yours and a supplier’s. A correlation sample of n=25 units was inspected using both gages. The std dev using gage #1 is 20, using gage #2 it is 30. What is critical value of the appropriate statistic to test the null hypothesis that the variances of both gages are equal at 5% significance (1-sided test)?

**a. 1.98 ** b. 2.25 c. 4.85 d. none of the above

9. The acceleration factor for increasing vibration from 50 units to 200 units is 6.4. At a vibration level of 200 units, the time to failure is lognormal with a scale parameter of 0.8 and a location parameter of 3.2. What is the reliability under normal conditions at time=100?

**a. 0.7136** b. 0.8271 c. 0.8361 d. none of the above

10. The equation below represents:

a. the Weibull distribution transformed for probability plotting

b. the Arrhenius model

c. the lognormal hazard function

**d. the linearized Eyring model**