Module 9 Review Questions

Module 9 Review Questions Answer the following multiple choice questions: 1. Following a dramatic drop of 500 points in the Dow Jones Industrial Average in September 1998, a poll conducted for the Associated Press found that 92% of those polled said that a year from now their family financial situation will be as good as it is today or better. The number 92% is a (a) Statistic (b) Sample (c) Parameter (d) Population (e) None of the above. The answer is . 2. In a large population, 46% of the households own VCR’s. A simple random sample of 100 households is to be contacted and the sample proportion computed. The mean of the sampling distribution of the sample proportion is (a) 46 (b) 0.46 (c) About 0.46, but not exactly 0.46 (d) 0.00248 (e) The answer cannot be computed from the information given 3. In the same setting as problem 2, what is the standard deviation of the sampling distribution of the sample proportion? (a) 46 (b) 0.46 (c) 0.00248 (d) 0.005 (e) None of the above. The answer is . 4. If a population has a standard deviation σ , then the standard deviation of the mean of 100 randomly selected items from this population is (a) σ (b) 100 σ (c) σ /10 (d) σ /100 (e) 0.1 5. The distribution of values taken by a statistic in all possible samples of the same size from the same population is (a) The probability that the statistic is obtained (b) The population parameter (c) The variance of the values (d) The sampling distribution of the statistic (e) None of the above. The answer is . 6. If a statistic used to estimate a parameter is such that the mean of its sampling distribution is equal to the true value of the parameter being estimated, the statistic is said to be (a) Random (b) Biased (c) A proportion (d) Unbiased (e) None of the above. The answer is . 7. A simple random sample of 1000 Americans found that 61% were satisfied with the service provided by the dealer from which they bought their car. A simple random sample of 1000 Canadians found that 58% were satisfied with the service provided by the dealer from which they bought their car. The sampling variability associated with these statistics is (a) Exactly the same. (b) Smaller for the sample of Canadians because the population of Canada is smaller than that of the United States, hence the sample is a larger proportion of the population. (c) Smaller for the sample of Canadians because the percentage satisfied was smaller than that for the Americans. (d) Larger for the Canadians because Canadian citizens are more widely dispersed throughout the country than in the United States, hence they have more variable views. (e) Almost the same. 8. The number of undergraduates at Johns Hopkins University is approximately 2000, while the number at Ohio State University is approximately 40,000. At both schools a simple random sample of about 3% of the undergraduates is taken. Which of the following is the best conclusion? (a) The sample from Johns Hopkins has less sampling variability than that from Ohio State. (b) The sample from Johns Hopkins has more sampling variability than that from Ohio State. (c) The sample from Johns Hopkins has almost the same sampling variability as that from Ohio State. (d) It is impossible to make any statement about the sampling variability of the two samples since the students surveyed were different. (e) None of the above. The answer is . 9. In a large population of adults, the mean IQ is 112 with a standard deviation of 20. Suppose 200 adults are randomly selected for a market research campaign. The distribution of the sample mean IQ is (a) Exactly normal, mean 112, standard deviation 20. (b) Approximately normal, mean 112, standard deviation 0.1. (c) Approximately normal, mean 112, standard deviation 1.414. (d) Approximately normal, mean 112, standard deviation 20. (e) Exactly normal, mean 112, standard deviation 1.414. 10. The law of large numbers states that, as the number of observations drawn at random from a population with finite mean µ increases, the mean x of the observed values (a) Gets larger and larger. (b) Gets smaller and smaller. (c) Gets closer and closer to the population mean µ . (d) Fluctuates steadily between one standard deviation above and one standard deviation below the mean. (e) Varies randomly about µ . Answers: 1. a 2. b 3. e, 4.98 4. c 5. d 6. d 7. e 8. b, remember that the sample size, not the population size is important here 9. c 10. c