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Answers to CRE questions in March 2019 Newsletter

1. X and Y are discrete random variables. The probability that X = 3 is 0.20 and the probability that Y = 4 is 0.30. The probability of observing that X = 3 and Y = 4 concurrently is closest to:
a. 0.06
b. 0.
c. 0.50
d. Cannot answer with the information provided.

2. The probabilities that three students will earn an A on an exam are 0.20, 0.25, and 0.30, respectively. If each student’s performance is independent of that of the other two students, the probability that all three students will earn an A is closest to:
a. 0.0150
b. 0.0075
c. 0.0010
d. 0.7500

3. The following table summarizes the availability of trucks with air bags and bucket seats at a dealership.
What is the probability of randomly selecting a truck with air bags and bucket seats?

a. 0.34
b. 0.57
c. 0.28
d. 0.16

4. The lower limit of a normal distribution is:
a. negative one
b. zero
c. one
d. negative infinity

5. Approximately 50 percent of all observations for a normally distributed random variable fall in the interval:
a. μ ± 2σ
b. μ ± 0.67σ
c. μ ± σ
d. μ ± 3σ

6. A depot receives an average of two engines per day to repair. The probability that they will receive 20 engines in 8 days is:
a. 3.66%
b. 16.56%
c. 6.40%
d. 5.59%

7. The approximate 99% confidence interval for the population mean based on a sample of 60 returns with a mean of 7% and a sample standard deviation of 25% is closest to:
a. 1.546% to 13.454%
b. 0.546% to 13.454%
c. -1.59% to 15.589%
d. 1.584% to 14.584%

8. What is the computed value of the test statistic that follows an F-distribution when sample variances are equal and the level of significance is 0.10?
a. 0.90
b. 0.05
c. 1.00
d. 0.10

9 A survey is taken to determine whether the average starting salaries of Reliability engineers is equal to or greater than $59,000 per year. What is the test statistic given a sample of 135 new Reliability engineers with a mean starting salary of $64,000 and a standard deviation of $5,500?
a. -0.91
b. -10.56
c. 10.56
d. 0.91

10. You have collected monthly returns to depot and want to test the null hypothesis that the standard deviation exceeds the advertised standard deviation of 3.5%. The most appropriate test statistic is based on
a. chi-square test
b. t-test
c. F-test
d. z-test

Picture © B. Poncelet

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Courses at RAMS 2022

The following special course is presented by ASQ’s Reliability and Risk Division at RAMS 2022. Registration linkSunday course canceledThursday,January 27, 2022andFriday,January 28, 2022Communicating Reliability, Risk, and Resiliency to Decision MakersJanuary 27, 2022, 1:00 p.m. – 5:00 p.m.and January 28, 2022, 8:00 a.m. – noonSonoran conference room at the El Conquistador Resort Getting your boss’s boss to understand is one

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