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Example 110


Example 110:  In a 2011 report by the CDF (Children’s Defense Fund), it was reported that a random sample of 29 black males with only a high school degree earned on average $25,418.  The standard deviation is estimated to be $5,500.  Use the sample data and a 95% confidence level to find the margin of error E and the confidence interval for µ.  A 95% confidence interval was constructed for white males, and it was found that the true mean income for white males with only a high school degree was between $33,215 and 37,399.  Comparing these two intervals, can we conclude there is a significant difference between incomes for the two groups? 


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