Question 420459
A random sample of 100 babies is obtained and the mean head circumference is found to be 4.06cm.  
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Assuming that the population standard deviation is known to be 1.6cm, use 0.05 significance level to test the claim that the mean head circumference of all two-month old babies is equal to 40.0cm
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Ho: u = 4.0 cm
Ha: u is not equal to 4.0 cm
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t(4.0) = (4.06-4)/[1.6/sqrt(100)] = 0.06/0.16 = 0.375
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p-value = 2*P(0.375< t < 100, when df = 99) = 2*0.3542 = 0.7085
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Conclusion: Since the p-value is greater tan 5%, fail to reject Ho.
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Cheers,
Stan H.