Constructing a confidence interval - The stemplot below lists the ages of applicants who were successful in winning promotion (based on data from "debating the use of statistical evidence in allegations of age discrimination," by barry and boland, American Statistician, vol 58 no. 2). Assume that the sample is a simple random sample and construct a 95% confidence interval estimate of the mean age of all such successful people. Compare the result to the confidence interval for the age of those who were not successful (see the example in this section).
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The solution gives 95% confidence interval for the mean age of people who are successful in winning promotion. A comparison is also made with the confidence of age of those who were not successful.