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1. A sample of 25 seniors from a large metropolitan area schooldistrict had a mean Math SAT score of 450. Suppose we know that thestandard deviation of the population of Math SAT scores for seniorsin the district is 100. A 90% confidence interval for thepopulation mean SAT score for the population of seniors is used.Which of the following would produce a confidence interval with asmaller margin oferror?                                                                                                  (2)

1. Using a sample of 100 seniors
2. Using a confidence level of 95%
3. Using an alpha (α) of 0.01
4. Using a sample of only 10 seniors

1. In a large population of adults, the mean IQ is 112 with astandard deviation of 20. Suppose 200 adults are randomly selectedfor a market research campaign. What is the sampling distributionof their sample mean IQ? Must show work (explain) to justifychoice.                                          (4)

1. exactly normal, mean 112, standard deviation 20
2. approximately normal, mean 112, standard deviation of 0.1
3. approximately normal, mean 112, standard deviation 1.414
4. approximately normal, mean 112, standard deviation 20

1. A final exam in Math 160 has a mean of 73 with a standarddeviation of 7.8. If 34 students are randomly selected, find theprobability that the mean of their test scores is more than76.   (6)

1. Given that a piece of data is from a distribution with a meanof 0 and a standard deviation of 1, find the amount of area underthe curve between z = – 1.83 and z =0.                                (3)

5. A study was conducted to estimate hospital costs for accidentvictims who wore seat belts. Twenty randomly selected cases to havea distribution that appears to be bell-shaped with a mean of $9004and a standard deviation of $5629. Construct the 99% confidenceinterval for the mean of all suchcosts.