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Confidence Interval & Sample size: Body Mass Index

1. The following are body mass index (BMI) scores measured in 12 patients who are free of diabetes and participating in a study of risk factors for obesity. Body mass index is measured as the ratio of weight in kilograms to height in meters squared. Generate a 95% confidence interval estimate of the true BMI.

25, 27, 31 ,33 ,26 ,28 ,38, 41, 24 ,32, 35, 40

2. Consider the data in Problem #1. How many subjects would be needed to ensure that a 95%
confidence interval estimate of BMI had a margin of error not exceeding 2 units?

Solution Summary

The solution provides step by step method for the calculation of confidence interval for mean and sample size. Formula for the calculation and Interpretations of the results are also included. Interactive excel sheet is included. The user can edit the inputs and obtain the complete results for a new set of data.