18. A concern that current recommendations on dietary energy requirements may underestimate the total energy needs of young adult men was the motivation for a study by Roberts et al, (A-14). Subjects for the study were 14 young, healthy adult men of normal body weight who were employed full-time in sedentary occupations as students or laboratory technicians. The following are the body mass index values (kg/m2) for the 14 subjects in the sample:

24.4 30.4 21.4 25.1 21.3 23.8 20.8 22.9 20.9 23.2 21.1 23.0 20.6 26.0

a. Compute the mean, median, variance, standard deviation, and coefficient of variation.

b. Construct a stem-and-leaf display.

c. Construct a box-and-whisker plot.

d. What percentage of the measurements are within one standard deviation of the mean? Within two standard deviations? Three standard deviations?