Name: _________________________________________
Date: _______________
11.2—Box-and-Whisker Plots
A box-and-whisker plot is a data display that organizes data values into 4 groups using the
median and quartiles. Each group represents _______% of the data.


Each whisker contains 25% of the data.
The box contains 50% of the data.
Example: Create a box-and-whisker plot for the data.
572 452 457 460 360 407 380 458 264
Steps to make a box-and-whisker plot:
1) Place data in order from least to greatest & determine a scale to use on your number line.
2) Mark the lower extreme (least data value) and the upper extreme (greatest data value).
3) Find the median of the entire data set (middle number). Write it in the space below and
mark it on your box-and-whisker plot.
4) The median breaks the data into two halves.
Find the median of each half of the data. Write them below and mark them on your plot.
 The median of the lower half of the data is called the ________ __________.

The median of the upper half of the data is called the ________ __________..
* The difference between the upper quartile and lower quartile is known as the
____________________ range (also called the IQR).
* The median, lower quartile, and upper quartile do not have to be original data values!
5) Draw the box from the lower quartile to the upper quartile. Then, draw a vertical line
through the median.
6) Draw a horizontal line (the “whiskers”) from the edge of the box to each of the extremes.
LE:
LQ:
Median:
UQ:
UE:
Practice: The data below represents the cost of a gallon of gas in different cities in 2010.
Create a box-and-whisker plot for the data. 2.25, 4.10, 1.93, 3.26, 2.82, 2.64, 3.08, 2.57
LE
LQ:
Median:
UQ:
UE:
Interpreting Box-and-Whisker Plots
The box-and-whisker plots represent the test scores for students in two different classes:
0
10
20
30
40
50
60
70
80
90
100
Class A
Class B
Write a paragraph comparing how these two classes did on this test. Give as much information as
you can.
1)
4)
5)
2)
6)
7)
3)