Obesity is a risk factor for many health problems such as type 2 diabetes, high blood pressure, joint problems, and gallstones. Using data collected in 2018 through the National Health and Nutrition Examination Survey, the National Institute of Diabetes and Digestive and Kidney Diseases estimates that 37.7% of all adults in the United States have a body mass index (BMI) in excess of 30 and so are categorized as obese. The data in the file Obesity are consistent with these findings.

a. Use the Obesity data set to develop a point estimate of the BMI for adults in the United States. Are adults in the United States obese on average? 

b. What is the sample standard deviation? 

c. Develop a 95% confidence interval for the BMI of adults in the United States.