A box plot is so named for its iconic shape:

(They can also be laid out horizontally). The parts of the graph correspond to:

Looking at a box plot can give you a quick sense of what the distribution of the data looks like. For example:

__Example 1__

Find the 25th percentile, 50th percentile, 75th percentile, range, and median for the below boxplot:

Answer
The 25th percentile on a box plot corresponds to the bottom segment of the rectangle, in this case 3. The 50th percentile is the line in the middle of the rectangle, here 4. And the 75th percentile is the top line of the rectangle, in this case 5.5. Now, the ends of the rectangle (the "whiskers") generally correspond to the most extreme values of the box plot, unless there are outliers (values that lie beyond the whiskers). We don't see any outliers here, so the range is found by just subtracting the whiskers: $9 - 2 = 7$. Finally, the median is just the 50th percentile, which we have already found is 4.

Example 2

[think of another example]

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