To find the range of the number of students per class for the top 25% of the classes, we need to determine the range of the upper quartile of the data.
The upper quartile (Q3) is represented by the top of the box in the box-and-whisker plot. We can see that the top of the box is at approximately 32 students.
To determine the range of the upper quartile, we need to find the value of the data point that represents the 75th percentile (Q3) and subtract it from the maximum value (the top whisker).
The range of the upper quartile is:
Range = Maximum - Q3
The maximum value is represented by the top whisker, which appears to be at approximately 48 students.
To find the value of Q3, we can use the median of the upper half of the data. The median of the upper half of the data is represented by the bottom of the box in the box-and-whisker plot, which appears to be at approximately 28 students.
Therefore, the range of the upper quartile is:
Range = Maximum - Q3 = 48 - 28 = 20
So the range of the number of students per class for the top 25% of the classes is 20.