Contaminated water: The concentration of benzene was measured in units of milligrams per liter for a simple random sample of five specimens of untreated wastewater produced at a gas field. The sample mean was 7.8 with a sample standard deviation of 1.4. Seven specimens of treated wastewater had an average benzene concentration of 3.2 with a standard deviation of 1.7. Assume that both samples come from normal populations. Can you conclude that the standard deviation of benzene concentration differs between treated water and untreated water? Use the a = 0.05 level of significance.
Answer to relevant QuestionsA company studied two programs for compensating its sales staff. Nine salespeople participated in the study. In program a sales people were paid a higher salary, plus a small commission for each item they sold. In program b ...The following 11-84 Plus calculator display presents the results of a hypothesis test for the difference between two means. The sample sizes are n1 = 18 and n2 = 16. a. Is this a left-tailed test, a right-tailed test, or a ...Test statistic: Compute the value of the chi- square statistic. In a hypothetical study, four hospitals were compared with regard to the outcome of a particular type of surgery. For each patient at each hospital, the ...Compute the value of the chi- square statistic. The General Social Survey polled 1280 men and 1531 women to determine their level of education. The results are presented in the following table. Use the data in Table 12.11 to test the null hypothesis that gender is independent of department. Show that this hypothesis is rejected at the. = 0.01 level. We conclude that department is associated with both gender and ...
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