Body mass index (BMI) is a measure of body fat based on height and weight. According to Dietary Guidelines for Americans, published by the U.S. Department of Agriculture and the U.S. Department of Health and Human Services, for adults, a BMI of greater than 25 indicates an above healthy weight (i.e., overweight or obese). The BMIs of 75 randomly selected U.S. adults provided the data on the Weiss-Stats site. Use the technology of your choice to do the following.
a. Obtain a normal probability plot, a boxplot, and a histogram of the data.
b. Based on your graphs from part (a), is it reasonable to apply the one-mean z-test to the data? Explain your answer.
c. At the 5% significance level, do the data provide sufficient evidence to conclude that the average U.S. adult has an above healthy weight? Apply the one-mean z-test, assuming a standard deviation of 5.0 for the BMIs of all U.S. adults.