1. 100 integrated circuits (ICs) are cycled in an environmental test chamber for a test equivalent to 1000 hours of operation. At the completion of the test, two of the units failed. The binomial distribution can be used to estimate reliability, and the F distribution can be used to calculate the confidence limit.
Estimate the reliability of the IC for a mission time of 1000 hours.
A. 0.952
B. 0.857
C. 0.947
D. 0.983
2. Battery life has been measured as normally distributed with a mean equal to 150 hours and a variance of 400 hours. Find the B10 life.
A. 128.1 hrs
B. 124.4 hrs
C. 122.6hrs
D. 110hrs
3. Failure rate data is acquired from MIL-HDBK-217 for reliability modeling of a new circuit board design. The failure rate for the entire circuit board is acquired by summing the MIL-HDBK-217 failure rates for each component on the circuit board. The most likely assumptions made by the engineer for this analysis are that individual component failure rates are _____ with time and are modeled in a ______ configuration.
A. Constant; series
B. Decreasing; series
C. Increasing; series
D. Constant; parallel
4. Each of the following test acceleration models is most often used with only one varying stress type, except for which?
A. Arrhenius
B. Coffin-Manson
C. Inverse Power Law
D. Eyring
5. A water pump is described by the reliability block diagram above. The 1,000-hour reliability of subsystems A and C are 0.95 and 0.98, respectively. Subsystem B has a failure rate of 0.00003 failures/hour. Assuming an exponential distribution, what is the system’s reliability at 1,000 hours?
A. 0.9034
B. 0.6897
C. 0.7986
D. 0.9546
6. Suppose that six bad golf balls get mixed up with eight good golf balls. If two balls are drawn simultaneously, what is the probability that both are good?
A. 0.1563
B. 0.3077
C. 0.2857
D. 0.3956
7. Which of the following choices is the best type of control chart for depicting the average number of defects found in a particular make and model of a refrigerator?
A. X-bar and R-chart
B. np chart
C. A normal curve
D. U chart
8. Sample Variance of resistance for the 20-unit sample of electronic components was 4 ohms. 95% confidence interval for the population variance is:
A. 2.31 ≤ σ2 ≤ 8.53
B. 2.93 ≤ σ2 ≤ 10.43
C. 2.52 ≤ σ2 ≤ 7.51
D. 3.18 ≤ σ2 ≤ 9.21
9. A product has been produced for many years with an average yield of 85% (That 85% is a lower 95% confidence limit). Ten batches were produced using a new raw material with a sample average yield of 86% and a standard deviation of 1%. At the 95% confidence level, the data indicate the average yield is:
A. less than the sample average yield of 86% and is statistically different
B. greater than the sample average yield of 86% and is statistically different
C. greater than the sample average yield of 86% and statistically there is no difference
D. less than the sample average yield of 86% and statistically there is no difference
10. 50 samples of an electronic component selected at random at incoming inspection measures an average resistance of 10 ohms and a standard deviation of 2 ohms. 95% confidence interval for the population mean is:
A. 9.53≤ μ≤ 10.47
B. 8≤ μ≤ 12
C. 6≤ μ≤14
D. 9.43≤ μ≤ 10.57
