Young people may feel they are carrying the weight of the world on their shoulders, when what they are actually carrying too often is an excessively heavy backpack. The article “Effectiveness of a School- Based Backpack Health Promotion Program” (Work 2003: 113–123) reported the following data for a sample of 131 sixth graders: for backpack weight (lb), x̅ = 13.83; s = 5.05; for backpack weight as a percentage of body weight, a 95% confidence interval for the population mean was (13.62, 15.89).
a. Calculate and interpret a 99% CI for population mean backpack weight.
b. Obtain a 99% CI for population mean weight as a percentage of body weight.
c. The American Academy of Orthopedic Surgeons recommends that backpack weight be at most 10% of body weight. What does your calculation of (b) suggest, and why?