Question 447603
In a new york modeling agency, a research wishes to see if the average height of female models is really less than 67 inches,as the chief claims. a sample of 20 models has an average height of 65.8 inches. the standard deviation of the sample is 1.7 inches. at a=0.05,is the average height of the models really less than 67 inches? use the p-value method .
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Ho: u >= 67 in. 
Ha: u < 67 (claim)
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t(65.8)= (65.8-67)/[1.7/sqrt(20)] = -3.1568
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p-value is P(t < -3.1568 when df = 19) = 0.0026
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Conclusion: Since the p-value is less than 5%, reject Ho
at the 5% level of significance.
The test results support the claim.
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cheers,
Stan H.