SOLUTION: the average local cell phone call length was reported to be 2.27 minutes. A random sample of 20 phone calls showed an average of 2.98 minutes with a standard deviation of 0.98 minu

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Question 851681: the average local cell phone call length was reported to be 2.27 minutes. A random sample of 20 phone calls showed an average of 2.98 minutes with a standard deviation of 0.98 minute. At 0.05 level of significance can it be concluded that the average differs from the population average?
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
the average local cell phone call length was reported to be 2.27 minutes. A random sample of 20 phone calls showed an average of 2.98 minutes with a standard deviation of 0.98 minute. At 0.05 level of significance can it be concluded that the average differs from the population average?
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Ho: p = 2.27 (claim)
Ha: p # 2.27
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x-bar = 2.98
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t(2.98) = (2.98-2.27)/[0.98/sqrt(20)] = 3.24
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p-value = 2*P(t > 3.24 when df = 19) = 2*tcdf(3.24,100) = 0.0051
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Conclusion: Since the p-value is less tahn 5% reject Ho.
The test results do not support the claim at the 5%
level of significance.
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Cheers,
Stan H.
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