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Exam 2 - Old Practice Exam a

# Exam 2 - Old Practice Exam a - Statistics 211 Practice Exam...

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Statistics 211 Practice Exam 2 Answer key 1. The formula E(X) = np can be used to find the expected value of a. any numeric random variable b. only Poisson random variables c. only normal random variables d. only binomial random variables * e. none of the above 2. For a specific sample size, the width of a 95% confidence interval on μ a. would be larger than the width of a 90% confidence interval on μ . * b. would be smaller than the width of a 90% confidence interval on μ . c. would be the same as the width of a 90% confidence interval on μ . d. cannot be compared to the width of a 90% confidence interval on μ . e. none of the above 3. A random sample of 400 WVU students was selected, in which 150 students stated that they had used “ an illegal drug”. A 95 % confidence interval on binomial parameter p goes from 33.5% to 41.5%. Which of the following statements provides the appropriate interpretation of this 95 % confidence interval? a. 95% of all WVU students use an illegal drug between 33.5% and 41.5% of the time. b. There is a 95% probability that a randomly selected WVU student has used an illegal drug. c. We are 95% confident that between 33.5% and 41.5% of all WVU students have used an illegal drug. * d. We are 95% confident that between 33.5% and 41.5% of the sample of 400 WVU students have used an illegal drug. e. none of the above 4. The standard normal distribution is a normal distribution whose a. mean is μ =1 and standard deviation σ =0 b. mean is μ =0 and standard deviation σ =1 * c. mean μ can have any real value and standard deviation σ =1 d. mean μ can be determined by using a z-score e. none of the above 5. A radar gun is used to measure the speed of 74 randomly selected automobiles on Interstate 79, and the data is used to construct a 95% confidence interval on the mean

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speed of all automobiles on I-79. The 95 % confidence interval goes from 64.4 mph to 71.6 mph. Which of the following statements provides the appropriate interpretation of this 95 % confidence interval? a. 95% of all automobiles on I-79 travel between 64.4 mph and 71.6mph. b. There is a 95% probability that the mean speed of all automobiles on I-79 is between 64.4 mph and 71.6 mph. c. We are 95% confident that the mean speed of all automobiles on I-79 is
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Exam 2 - Old Practice Exam a - Statistics 211 Practice Exam...

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