PracticeExamNumber1

# PracticeExamNumber1 - 1 A B C D Other things being equal...

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1. Other things being equal, the margin of error of a confidence interval increases as A) the sample size increases. B) the confidence level decreases. C) the population standard deviation increases. D) none of the above. 2. A study was conducted to compare the weights of sedentary workers with the weights of workers in physically demanding jobs. As part of the study, the weights of male accountants between the ages of 35 and 50 were recorded. Suppose a 99% confidence interval for the mean weight of accountants in pounds is (172.3, 176.5). If we had measured the weights of each of the accountants in kilograms (2.2 pounds = 1 kilogram), then the confidence interval for the mean weight of such accountants in kilograms would have been A) (174.5, 176.7). B) (78.32, 80.23). C) (379.06, 388.3). D) (170.1, 174.3). 3. Is the mean height for all adult American males between the ages of 18 and 21 now over 6 feet? If the population of all adult American males between the ages of 18 and 21 has mean height of P feet and standard deviation V feet, to answer this question one would test which of the following null and alternative hypotheses? A) H 0 : = 6 vs. H a : > 6 B) H 0 : = 6 vs. H a : < 6 C) H 0 : = 6 vs. H a : z 6 D) H 0 : = 6 vs. H a : = 6 ± x , assuming our sample size is n . 4. In a test of significance, assuming the null hypothesis is true, the probability that the test statistic will take a value at least as extreme as that actually observed is A) the P -value of the test. B) the level of significance of the test. C) the probability the null hypothesis is true. D) the probability the null hypothesis is false. Page 1

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5. In a test of statistical hypotheses, the P -value tells us A) if the null hypothesis is true. B) if the alternative hypothesis is true. C) the largest level of significance at which the null hypothesis can be rejected. D) the smallest level of significance at which the null hypothesis can be rejected. 6. The nicotine content in cigarettes of a certain brand is normally distributed, with mean (in milligrams) P and standard deviation V = 0.1. The brand advertises that the mean nicotine content of its cigarettes is 1.5, but measurements on a random sample of 100 cigarettes of this brand give a mean of x = 1.53. Is this evidence that the mean nicotine content is actually higher than advertised? To answer this, test the hypotheses H 0 : = 1.5, H a : > 1.5 at the 5% significance level. You conclude A) that H 0 should be rejected. B) that H 0 should not be rejected. C) that H a should be rejected. D) there is a 5% chance that the null hypothesis is true. 7. An agricultural researcher plants 25 plots with a new variety of corn that is drought resistant and hence potentially more profitable. The average yield for these plots is x = 150 bushels per acre. Assume that the yield per acre for the new variety of corn follows a normal distribution with unknown mean and that a 95% confidence interval for is found to be 150 ± 3.29. Which of the following is true?
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## This note was uploaded on 09/25/2009 for the course IDS 371 taught by Professor Staff during the Spring '08 term at Ill. Chicago.

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PracticeExamNumber1 - 1 A B C D Other things being equal...

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