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Unformatted text preview: 12: INFERENCE ABOUT A POPULATION MULTIPLE CHOICE QUESTIONS In the following multiplechoice questions, please circle the correct answer. 1. In selecting the sample size to estimate the population proportion p , if we have no knowledge of even the approximate values of the sample proportion p ˆ , we: a. take another sample and estimate p ˆ b. take two more samples and find the average of their p ˆ c. let p ˆ = 0.50 d. let p ˆ = 0.95 ANSWER: c 2. Under which of the following circumstances is it impossible to construct a confidence interval for the population mean? a. A nonnormal population with a large sample and an unknown population variance b. A normal population with a large sample and a known population variance c. Nonnormal population with a small sample and an unknown population variance d. A normal population with a small sample and an unknown population variance ANSWER: c 3. The use of the standard normal distribution for constructing confidence interval estimate for the population proportion p requires: a. p n ˆ and p n ˆ 1 ( ) are both greater than 5, where p ˆ denotes the sample proportion b. np and n (1 p ) are both greater than 5 c. n ( p + p ˆ ) and n ( p p ˆ ) are both greater than 5 d. that the sample size is greater than 5 ANSWER: a 4. The lower limit of a confidence interval at the 95% level of confidence for the population proportion if a sample of size 200 had 40 successes is: a. 0.2554 b. 0.1446 c. 0.2465 d. 0.1535 ANSWER: b 5. Assuming that all necessary conditions are met, what needs to be changed in the formula n p p t p / ) ˆ 1 ( ˆ ˆ ± α so that we can use it to construct a confidence interval estimate for the population proportion p ? a. The p ˆ should be replaced by p b. The α t should be replaced by α z c. The α t should be replaced by 2 / α t d. The α t should be replaced by 2 / α z ANSWER: d 6. Suppose that a onetail t test is being applied to find out if the population mean is less than 100. The level of significance is 0.05 and 25 observations were sampled. The rejection region is: a. t > 1.708 b. t < 1.711 c. t > 1.318 d. t < 1.316 ANSWER: b 7. A random sample of size n has been selected from a normally distributed population whose standard deviation is σ . In hypothesis testing for the population mean, the t test should be used instead of the z test if: a. n > 30 and σ is unknown b. n < 30 and σ is unknown c. n < 30 and σ is known d. both (a) and (c) ANSWER: d 8. As its degrees of freedom increase, the chisquared distribution approaches the shape of the: a. Student...
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This document was uploaded on 10/25/2011 for the course LAPS 2320 at York University.
 Fall '10
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