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Example 122


Example 122:  In a 2007 study of different popular diets, 77 people used a modified* version of the Atkins Diet for one year.  Their mean weight change was -10.34 lbs.  Assume that the population standard deviation for all such weight changes is known to be 15.51 pounds.  Use a significance level of 0.05 to test the claim that the mean weight change is equal to zero.  Does the diet seem to be effective?  Does the mean weight change seem substantial enough to justify the diet?  What assumptions are necessary for the test we just conducted to be valid?

*The Atkins diet was modified to include higher levels of fiber and high quality complex carbohydrate.  


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