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Example 146


Example 146 In 1995, the American Cancer Society randomly sampled 1500 adults of which 555 smoked.  In 2005, they surveyed 1750 adults and found that 578 of them smoked.  Form a 90% confidence interval for the difference between the proportion of smokers in 1995 and 2005.  Has the proportion decreased over the ten year period? 


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