Stats Practice Exam Questions With Complete Solutions

Refer to the accompanying data display that results from a sample of airport data speeds in Mbps. Complete parts (a) through (c) below. TInterval (13.046,22.15) x=17.598 Sx=16. n=50 a.Express the confidence interval in the format that uses the "less than" symbol. Given that the original listed data use one decimal place, round the confidence interval limits accordingly. b.Identify the best point estimate of μ and the margin of error. c. In constructing the confidence interval estimate of μ, why is it not necessary to confirm that the sample data appear to be from a population with a normal distribution? A. Because the sample standard deviation is known, the normal distribution can be used to construct the confidence interval. B. Because the population standard deviation is known, the normal distribution can be used to construct the confidence interval. C. Because the sample size of 50 is greater than 30, the distribution of sample means can be treated as a normal distribution. Your answer is correct. D. Because the sample is a random sample, the distribution of sample means can be treated as a normal distribution. correct answer: a: take what's in the parentheses, round as needed. Enter as 13.05μ22.15 b. Since μ is represented in this problem by x, simply round as needed. For E take the upper limit, subtract from the lower limit, and divide by 2. In this instance, it would be (22.15-13.046)/2 =4.55 c. Evaluate your data to determine the right answer. In this instance, it's C The notation P(za) denotes _______. correct answer: the probability that the z-score is less than a. Discrete vs. Continuous Variables correct answer: Discrete: A finite number of values between any two values. A discrete variable is always numeric. For example, the number of customer complaints or the number of flaws or defects. Continuous: An infinite number of values between any two values. A continuous variable can be numeric or date/time. For example, the length of a part or the date and time a payment is received. Determine whether the value is a discrete random variable, continuous random variable, or not a random variable. The distance a baseball travels in the air after being hit correct answer: It is a continuous random variable. Is the number of textbook authors now sitting at a computer a discrete random variable, a continuous random variable, or not a random variable? A. It is a discrete random variable. Your answer is correct. B. It is a continuous random variable. C. It is not a random variable correct answer: It is a discrete random variable Is the political party affiliation of adults in the United States a discrete random variable, a continuous random variable, or not a random variable? A. It is a discrete random variable. B. It is a continuous random variable. C. It is not a random variable. correct answer: It is not a random variable Is the number of free-throw attempts before the first shot is made a discrete random variable, a continuous random variable, or not a random variable? A. It is a continuous random variable. B. It is a discrete random variable. C. It is not a random variable. correct answer: It is a discrete random variable Is the square footage of a house a discrete random variable, a continuous random variable, or not a random variable? A. It is a discrete random variable. B. It is a continuous random variable. C. It is not a random variable. correct answer: It is a continuous random variable