Common Core State Standards >> Mathematics >> 7SP3

Question: Do students in higher grades tend to carry heaver backpacks?

I grouped the students in the lower and higher grades together by dragging the icons to 1) combine grades 1 and 3 and combine grades 5 and 7 into two horizontal bins. Then, I found the mean pack weight for each group and used the ruler tool to to find the difference of the two means.

The students in the upper grades carry backpacks that are, on average, 8.4 pounds higher than the students in the lower grades.
BackPackGradeWeight.png
However, a friend of mine said that the two students with the really heavy backpacks could have been included in the sample on a day that he or she carried something they would not typically carry. So, I used a filter to remove the 27 and 39 pound packs.
BackPackWeightFiltered.png
The graph above shows a difference of about 7.5 pounds for the two different grade level bands. This might be a more realistic difference between the average backpack weights for this group of students. Conclusion: Yes, the students in the upper grades tend to carry heavier backpacks.

Note that we should limit our analysis to this particular group of students