This graph compares shoe sizes for a group of 80 two-year-old boys and a group of 60 three-year-old boys. Two box and whisker plots showing shoes sizes on a number line from 2.5 to 13. The upper plot represents the group of 2 year-old boys. For this upper plot, the minimum number is 3, the maximum number is 9.5, the right side of the box is 7.5, the left side of the box is 3.5, and the bar in the box is at 6. The lower plot represents the group of 3 year-old boys. For this lower plot, the minimum number is 5, the maximum number is 11.5, the right side of the box is 9.5, the left side of the box is 6.5, and the bar in the box is at 8. About how many more two-year-old boys have a shoe size of 6 or less, compared to the three-year-old boys?

To determine about how many more boys have a shoes size of 6 or less, you need to understand that a box and whisker plot takes a data set and show it in quarters (25% of the data is represented in each section).

For the 2 years olds, if the box in the middle, that means that half of the boys have a shoe size at 6 or under.  There were 80 boys chosen for this study, so half of that is 40.

For the 3 year olds, the closest point to 6 is 6.5, and it is located after the line on the left.  This means that only 25% of the boys have shoe sizes of 6.5 or under.  25% of the 60 three-year olds they collected data on is 15.

The difference is 40-15= 25.
There are about 25 more two-year olds wearing a size 6 or under.