SOLUTION: Last year the records of Dairy Land Inc., a convenience store chain, showed the mean amount spent by a customer was $30. A sample of 40 transactions this month revealed the mean am

Question 143139: Last year the records of Dairy Land Inc., a convenience store chain, showed the mean amount spent by a customer was $30. A sample of 40 transactions this month revealed the mean amount spent was $33 with a standard deviation of $12. At the 0.05 significance level, can we conclude that the mean amount spent has increased? What is the p-value? Follow the five-step hypothesis testing procedure.
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
Last year the records of Dairy Land Inc., a convenience store chain, showed the mean amount spent by a customer was $30. A sample of 40 transactions this month revealed the mean amount spent was $33 with a standard deviation of $12. At the 0.05 significance level, can we conclude that the mean amount spent has increased? What is the p-value? Follow the five-step hypothesis testing procedure.
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Ho: u = 30
Ha: u > 30
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test statistic:
z(33) = (33-30)/[12/sqrt(40)] = 1.5812...
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p-value = P(1.5812 < z < 10) = 0.056923...
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Conclusion: Sinc p-value is greater than 5%, fail to reject Ho.
The mean amount spent is $30; it has not increased.
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Cheers,
Stan H.
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