15. IQ and Lead Exposure Standard IQ tests are designed to yield a population mean of 100. Data Set 11 "IQ and Lead" in Appendix B includes IQ scores of 21 children with high expo- sure to lead. For this group, the IQ scores have a mean of 86.90476 and a standard deviation of 8.988352. Use a 0.05 significance level to test the claim that this sample is from a population with mean IQ equal to 100. Do the results prove that exposure to lead has an adverse effect on IQ scores of children? di R

You may need to use the appropriate appendix table or technology to answer this question. At Western University the historical mean of scholarship examination scores for freshman applications is 900. A historical population standard deviation = 180 is assumed known. Each year, the assistant dean uses a sample of applications to determine whether the mean examination score for the new freshman applications has changed. (a) State the hypotheses. OH₂H ≤ 900 H₂:μ > 900 H:μ ≥ 900 H: μ 900 H:μs 900 (b) What is the 95% confidence interval estimate of the population mean examination score if a sample of 190 applications provided a sample mean x = 933? (Round your answers to the nearest integer.) to (c) Use the confidence interval to conduct a hypothesis test. Using a = 0.05, what is your conclusion? O Reject H. There is sufficient evidence to conclude that the mean examination score for the new freshman applications has changed. O Reject H. There is insufficient evidence to conclude that the…

Home prices in a city have mean = $194,000 and standard deviation = $20,000. For n = 25 randomly selected homes, the mean price is x = $198,000. Find the value of the standardized statistic (z- score) for this sample mean. z = USE SALT

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