How to Create Box-and-whisker Graph

Are your students struggling with creating box and whisker graphs? Here are some directions and presentations that can help students quickly learn how to put the right numbers in the right place. The first version is only in PDF and the second contains the first and is fully customizable, or you can just read through the steps listed below.

• @worksheetshare.com How to Create a Box-and-whisker Graph PDF only version
• @TeachersPayTeachers.com How to Create a Box-and-whisker Graph OpenOffice/PowerPoint/PDF

The OpenOffice/PowerPoint versions contain simple animations and timings to help the presentation flow smoothly but the PDF version can work if you don't have access to OpenOffice or MS PowerPoint.

Vocabulary
Median
The middle value when all of the data values are placed in order.

Quartile
One forth or one quarter of the data.

Extreme
Value that is far from the rest of the data.
The largest and smallest value.

Example Problem
The owner of a gas station wants you to make a box-and-whisker graph to represent the number of people who came purchased gas each day.

Data

17 21 16 22 24 26 18 28 25 29 21 18 14 23 25 18 26 24 22 23

Follow these steps:

1. Order the data
2. Find extremes
3. Find the median
4. Find the quartiles
5. Make your graph

Step 1: Order the data
A line plot or stem-and-leaf plot are the quickest ways to get your data in ascending order.

14 16 17 18 18 18 21 21 22 22 23 23 24 24 25 25 26 26 28 29

Step 2: Find the extremes
The lower extreme is 14, the smallest number.
The upper extreme is 29, the largest number.

Step 3: Find the median
Count the number of data items, which in this set happens to be 20.
Then divide the data into two equal parts, 10 on each side.

14 16 17 18 18 18 21 21 22 22

23 23 24 24 25 25 26 26 28 29

Since there is no middle value we need to take the average of one value from each side, 22 and 23. To find the average evaluate the following expression:

(22+23)÷2=22.5

The median is 22.5.

Step 4: Find the quartiles
Now divide each of the halves in half. Since each half contains 10 (even) items the middle is between the 5th and 6th value.


Data:

14 16 17 18 18

18 21 21 22 22

23 23 24 24 25

25 26 26 28 29

Take the average of the two values.
(18+18)÷2=18
(25+25)÷2=25

The lower quartile is 18.
The upper quartile is 25.

Step 5: Use the information to make your graph.