Nt1330 Unit 3 Case Study

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Question 1: Independent random samples from two normally distributed populations give the following results: nX = 10 x̅ = 480 sx = 30 ny = 12 y̅ = 520 sy = 25 a. If we assume that unknown population variances are equal, what is the 90% confidence interval for the difference of population means? b. If we do not assume that the unknown population variances are equal, find the 90% confidence interval for the difference between the population means. Question 2: A newspaper article reported that 400 people in one state were surveyed and 75% were opposed to a recent course decision. The same article reported that a similar survey of 500 people in another state indicated opposition by only 45%. Construct a 95% confidence interval of the difference in population proportions based on data.…show more content…
Test the null hypothesis that the home wins one-half of all games against the alternative that the home team wins a majority of games. Question 4: A process produces cable for the local telephone company. When the process is operating correctly, cable diameter follows a normal distribution with mean 1.6 inches and standard deviation 0.05 inch. A random sample of 16 pieces of cable found diameters with a sample mean of 1.615 inches and a sample standard deviation of 0.086 inch. a. Assuming that the population standard deviation is 0.05 inch, test at the 10% level against a two-sided alternative the null hypothesis that the population mean is 1.6 inches. Find also the lowest level of significance at which this null hypothesis can be rejected against the two-sided alternative. b. Test at the 10% level the null hypothesis that the population standard deviation is 0.05 inch against the alternative that is

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