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Confidence Intervals and Sample Size for Juice Bottles

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1. The amounts (in ounces) of juice in eight randomly selected juice bottles are:

15.4 15.7 15.2 15.8 15.8 15.4 15.0 15.6

Assuming the population of amounts in juice bottles is known to be normally distributed, create a 95% confidence interval estimate for , the mean amount of juice in all bottles.

You will be asked to identify x-bar, s, , df, t, E and the confidence interval. (3 points each)

2. Previous studies have indicated the standard deviation of annual earnings for college students is $850. How large a sample would need to be taken to estimate the mean for college students' annual earnings to within $200 with 99% confidence? (4.5 points)

3. A researcher is interested in estimating the proportion of voters who favor a tax on e-commerce. How large a sample would she need to collect to estimate this proportion to within 5% with 95% accuracy? (4.5 points)

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Solution Summary

The solution provides step by step method for the calculation of confidence interval and sample size for population mean and proportion. Formula for the calculation and Interpretations of the results are also included.