A random sample of n1 = 16 winter days in Denver gave a sample mean pollution index x1 = 43. Previous studies show that ?1 = 15. For Englewood (a suburb of Denver), a random sample of n2 = 14 winter days gave a sample mean pollution index of x2 = 37. Previous studies show that ?2 = 17. Assume the pollution index is normally distributed in both Englewood and Denver. Do these data indicate that the mean population pollution index of Englewood is different (either way) from that of Denver in the winter? Use a 1% level of significance. (a) What is the level of significance?   State the null and alternate hypotheses. H0: ?1 < ?2; H1: ?1 = ?2H0: ?1 = ?2; H1: ?1 > ?2    H0: ?1 = ?2; H1: ?1 ≠ ?2H0: ?1 = ?2; H1: ?1 < ?2 (b) What sampling distribution will you use? What assumptions are you making? The standard normal. We assume that both population distributions are approximately normal with unknown standard deviations.The standard normal. We assume that both population distributions are approximately normal with known standard deviations.    The Student's t. We assume that both population distributions are approximately normal with unknown standard deviations.The Student's t. We assume that both population distributions are approximately normal with known standard deviations. What is the value of the sample test statistic? (Test the difference ?1 − ?2. Round your answer to two decimal places.)   (c) Find (or estimate) the P-value. (Round your answer to four decimal places.)

Glencoe Algebra 1, Student Edition, 9780079039897, 0079039898, 2018
18th Edition
ISBN:9780079039897
Author:Carter
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Chapter10: Statistics
Section10.1: Measures Of Center
Problem 9PPS
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A random sample of n1 = 16 winter days in Denver gave a sample mean pollution index x1 = 43. Previous studies show that ?1 = 15. For Englewood (a suburb of Denver), a random sample of n2 = 14 winter days gave a sample mean pollution index of x2 = 37. Previous studies show that ?2 = 17. Assume the pollution index is normally distributed in both Englewood and Denver. Do these data indicate that the mean population pollution index of Englewood is different (either way) from that of Denver in the winter? Use a 1% level of significance.
(a)
What is the level of significance?
 
State the null and alternate hypotheses.
H0: ?1 < ?2H1: ?1 = ?2H0: ?1 = ?2H1: ?1 > ?2    H0: ?1 = ?2H1: ?1 ≠ ?2H0: ?1 = ?2H1: ?1 < ?2
(b)
What sampling distribution will you use? What assumptions are you making?
The standard normal. We assume that both population distributions are approximately normal with unknown standard deviations.The standard normal. We assume that both population distributions are approximately normal with known standard deviations.    The Student's t. We assume that both population distributions are approximately normal with unknown standard deviations.The Student's t. We assume that both population distributions are approximately normal with known standard deviations.
What is the value of the sample test statistic? (Test the difference ?1 − ?2. Round your answer to two decimal places.)
 
(c)
Find (or estimate) the P-value. (Round your answer to four decimal places.)
 
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