Math 160 CC American Chiropractic Association Discussion


Learn by Doing

Here are the directions, grading rubric, and definition of high-quality feedback for the Learn by Doing discussion board exercises.


Students researching backpack weights gathered data from 45 elementary school children in the 3rd and 5th grades. The variable is “percent of body weight carried in the school backpack.” So a child who weighs 60 pounds and carries 9 pounds has a variable value of 15% (9 ÷ 60 = 0.15 = 15%). The American Chiropractic Association (ACA) recommends that children carry no more than 10% of their body weight.


When we analyze backpack weight as a percentage of body weight, how do 3rd and 5th graders compare? Are children in this study following the ACA recommendation?

distribution of percent-of-body-weight carried: stacked histograms (3rd graders, 5th graders)

% of body weight carried in backpack Third
0-5% 1 1
5-10% 6 6
10-15% 11 4
15-20% 3 7
20-25% 0 1
25-30% 0 2
30-35% 0 1
Totals 21 22

Note: Left-hand end-points are included in each bin. So the 2nd bin contains students carrying 5% of their body weight.