Question 142904: The Rocky Mountain district sales manager of Rath Publishing, Inc., a college textbook publishing company, claims that the sales representatives make an average of 40 sales calls per week on professors. Several reps say that this estimate is too low. To investigate, a random sample of 28 sales representatives reveals that the mean number of calls made last week was 42. The standard deviation of the sample is 2.1 calls. Using the 0.05 significance level, can we conclude that the mean number of calls per salesperson per week is more than 40? (Remember to complete the 5 step hypothesis testing procedure to answer this question).
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! The Rocky Mountain district sales manager of Rath Publishing, Inc., a college textbook publishing company, claims that the sales representatives make an average of 40 sales calls per week on professors. Several reps say that this estimate is too low.
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Ho : u = 40
Ha : u > 40
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To investigate, a random sample of 28 sales representatives reveals that the mean number of calls made last week was 42. The standard deviation of the sample is 2.1 calls. Using the 0.05 significance level, can we conclude that the mean number of calls per salesperson per week is more than 40?
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Critical value for one-tail test with alpha-5% and df=27: t = 1.703
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Test statistic:
t(42) = (42-40)/[2.1/sqrt(28)] = 5.0395
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Conclusion:
Since the test statistic is in the rejection interval reject Ho.
We conclude that, based on this test, the mean number of calls is
more than 40.
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Cheers,
Stan H.
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