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# Calculating Confidence Intervals and Proportion

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Problem 4.1: Given the data set body-weight.sav, use SPSS to calculate the 90%, 95% and 99% confidence intervals for the mean of the variable weight. Interpret the three confidence intervals in terms of whether there is a significant difference between the mean of the sample and a hypothesized mean of 150.

Problem 4.2: Every year the CDC conducts phone surveys to assess the health risks of people in the U.S. This survey is abbreviated BRFSS, which stands for Behavioral Risk Factor Surveillance System. Review the following data collected for 2009:
Total number of respondents Number of respondents who smoke everyday Number of respondents who smoke some days Number of respondents who are former smokers Number of respondents who have never smoked
426,000 54,815 21,581 110,060 143,619

Calculate the proportion of each group of respondents.
Calculate the confidence interval for the proportion of respondents who stated they are former smokers.