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Test 3 Review: Chapters 7-9 Probability & Statistics WEST. Name, Solve the problem. 1) A 90% confidence interval for the average salary of all CEOs in the electronics industry was 1) constructed using the results of a random survey of 45 CEOs. ‘The interval was ($99,943, $113,695). Give a practical interpretation of the interval. A) 90% of the sampled CEOs have salaries that fell in the interval $99,943 to $113,695. B) We are 90% confident that the mean salary of all CEOs in the electronics industry falls in the interval $99,943 to $113,695. C)} We are 90% confident that the mean salary of the sampled CEOs falls in the interval $99,943 to $113,695, D) 90% of all CEOs in the electronics industry have salaries that fall between $99,943 to $113,695. 2) A random sample of 250 students at a university finds that these students take a mean of 15.6 credit 2) hours per quarter with a standard deviation of 2.2 credit hours, Estimate the mean credit hours taken by a student each quarter using a 99% confidence interval. A) 15.6 + .023 B) 15.6 + 358 C) 15.6 + 015 D) 15.6 + 242 3) Find the value of tg such that the following statement is true: P(-ip <# < #9) = .90 where df = 14. 3) A) 1,345 B) 2.624 C) 2.145 D) 1.761 4) To help consumers assess the risks they are taking, the Food and Drug Administration (FDA) 4) publishes the amount of nicotine found in all commercial brands of cigarettes. A new cigarette has recently been marketed. The FDA tests on this cigarette yielded mean nicotine content of 28.9 milligrams and standard deviation of 2.4 milligrams for a sample of n = 9 cigarettes. Construct a 99% confidence interval for the mean nicotine content of this brand of cigarette. A) 28.9 + 2.684 B) 28.9 + 2.600 C) 28.9 4 2.758 D) 28.9 + 2,847 5) We intend to estimate the average driving time of Chicago commuters. From a previous study, we 5) believe that the average time is 42 minutes with a standard deviation of 6 minutes. We want our 99 percent confidence interval to have a margin of error of no more than plus or minus 2 minutes. What is the smallest sample size that we should consider? Aj8 B) 120 C60 Dy) 10 6) How many tissues should a package of tissues contain? Researchers have determined that a person —_ 6) uses an average of 42 tissues during a cold, Suppose a random sample of 10,000 people yielded the following data on the number of tissues used during a cold: x =37,8= 25. Identify the null and alternative hypothesis for a test to determine if the mean number of tissues used during a cold is less than 42. A) Ho: p= 42 vs. Ha: je < 42 B) Ho: 1 > 42 vs. Ha: ps 42 C) Ho: p= 42 vs. Ha! we 42 D) Ho: p = 42 vs. Ha: p> 42 
