The Body Mass Index (BMI) is a value calculated based on the
weight and the height of an individual. In a small European city, a
survey was conducted one year ago to review the BMI of the
citizens. In the sample with 200 citizens, the mean BMI was 23.3
kg/m2 and standard deviation was 1.5 kg/m2. It is reasonable to
assume the BMI distribution is a normal distribution.
(a) Find the point estimate of the population mean BMI one
year ago.
(b) Calculate the sampling error at 90% confidence.
(c) Construct a 90% confidence interval estimate of the
population mean BMI one year ago.
This city launched a healthy exercise program to reduce
citizen’s BMI after last year’s survey.
program effectively reduces the BMI of each citizen by
2.5%.
(d) Construct a 98% confidence interval estimate of the
population mean BMI after the healthy exercise
program. (Hint: find the updated sample mean and sample
standard deviation of the BMI of the sample with 200 citizens
selected last year)