A random sample of n1 = 14 winter days in Denver gave a sample mean pollution index x1 = 43. Previous studies show that ?1 = 21. For Englewood (a suburb of Denver), a random sample of n2 = 16 winter days gave a sample mean pollution index of x2 = 35. Previous studies show that ?2 = 17. Assume the pollution index is normally distributed in both Englewood and Denver. What is the value of the sample test statistic? Compute the corresponding z or t value as appropriate. (Test the difference ?1 − ?2. Round your answer to two decimal places.) (iii) Find (or estimate) the P-value. (Round your answer to four decimal places.) (b) Find a 99% confidence interval for ?1 − ?2. (Round your answers to two decimal places.)
A random sample of n1 = 14 winter days in Denver gave a sample mean pollution index x1 = 43. Previous studies show that ?1 = 21. For Englewood (a suburb of Denver), a random sample of n2 = 16 winter days gave a sample mean pollution index of x2 = 35. Previous studies show that ?2 = 17. Assume the pollution index is
What is the value of the sample test statistic? Compute the corresponding z or t value as appropriate. (Test the difference ?1 − ?2. Round your answer to two decimal places.)
(iii) Find (or estimate) the P-value. (Round your answer to four decimal places.)
(b) Find a 99% confidence interval for ?1 − ?2. (Round your answers to two decimal places.)
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