Question 320267
 The average yearly cost per household of owning a dog is $194.21. 
Suppose that we randomly select 30 households that own a dog. 
What is the probability that the sample mean for these 30 households 
is less than $187.00? 
Assume standard deviation = $27.
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Sample mean: 187
t(187)=(187-194.21)/[27/sqrt(30)] = -1.4626
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P(x < 187) = P(t< -1.4626 when df=29) = tcdf(-1000,-1.4626,29) = 0.0772
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Cheers,
Stan H.