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Unformatted text preview: GE 331 / IE 300 Selected Exam II Questions from Previous Years PART I 1) Suppose a sample of size 25 is taken from a normal distribution the population mean of which is unknown and the population variance is 9. Which of the following is false for 0< <1: a) X 5 3 z has smaller confidence level than X 5 3 z b) X  5 3 z , X + 5 3 z has smaller confidence level than X 5 3 z c) The length of a symmetrical interval does not change with the confidence level for the samples of the same size. d) Both ( X  5 3 z , ) and X 5 3 z have the same confidence level although their lengths are very different. Answer: B and C 2) H o : o H 1 : > o Consider the following cases: (I) True population mean is o and the sample size is n. (II) True population mean is o + and the sample size is n. (III) True population mean is o and the sample size is 2n. (IV) True population mean is o + and the sample size is 2n. (V) True population mean is o and the sample size is 3n Order the probability of failing to reject Ho under each case. (For instance, I>II>III... etc.) Answer: III > I > V > II > IV n 2n 3n o o+ o II I III IV V 3) Given a random sample X 1 , X 2 ,,X n from an infinite population: a) Even for large n, say more than 40, the sample mean may not be normally distributed b) In terms of unbiasedness, X 1 is as good as X . c) In terms of MSE, X 1 is as good as X . d) Population mean is a function of the random sample. Answer: B 4) Parameters are a) numerical characteristics of a sample b) numerical characteristics of a population c) the averages taken from a sample d) numerical characteristics of either a sample or a population Answer: B 5) In point estimation a. data from the population is used to estimate the population parameter b. data from the sample is used to estimate the population parameter c. data from the sample is used to estimate the sample statistic d. the mean of the population equals the mean of the sample Answer: B 6) The standard deviation of all possible values is called the a. standard error of proportion b. standard error of the mean c. mean deviation d. central variation Answer: B 7) Whenever the population has a normal probability distribution, the sampling distribution of is a normal probability distribution for a. only large sample sizes b. only small sample sizes c. any sample size d. only samples of size thirty or greater Answer: C 8) A population has a standard deviation of 16. If a sample of size 64 is selected from this population, what is the probability that the sample mean will be within 2 of the population mean?...
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 Spring '09
 Zafarani

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