Question 2
The Body Mass Index (BMI) is a value calculated based on theweight and the height of an individual. In a
small European city, a survey was conducted one year ago toreview the BMI of the citizens. In the sample
with 200 citizens, the mean BMI was 23.3 kg/m2 and standarddeviation 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 oneyear ago.
(b) Calculate the sampling error at 90% confidence.
(c) Construct a 90% confidence interval estimate of thepopulation mean BMI one year ago.
This city launched a healthy exercise program to reducecitizen’s BMI after last year’s survey. Suppose the
program effectively reduces the BMI of each citizen by2.5%.
(d) Construct a 98% confidence interval estimate of thepopulation mean BMI after the healthy exercise
program. (Hint: find the updated sample mean and samplestandard deviation of the BMI of the sample
with 200 citizens selected last year)
