3.4 Box-and-Whisker Plots (
)
Math 7
Vocabulary/Rules
*** Box-and-Whisker Plot: displays data beneath a
number line that represents the range of data.
It includes the median, the upper extreme, the
lower extreme, the upper quartile, and the lower
quartile.
The data is divided into 4 parts.
*** Lower Quartile: the median of the lower half of
the data.
*** Upper Quartile: the median of the upper half of
the data.
***Lower Extreme: the least data value.
***Upper Extreme: the greatest data value.
*** Interquartile Range: the difference between the
quartiles. It is the measure of the spread of data.
Examples
** Ex. 1: Making a Box-and-Whisker Plot
The heights, in feet, of 10 suspended roller coasters
in the United States are 35, 42, 42.5, 60, 60, 70,
76, 78, 81, and 100. Make a box-and-whisker
plot of the data.
** Ex. 2: Interpreting a Box-and-Whisker Plot
*** The large box represents about ½ of the data.
*** Each small box represents about ¼ of the data.
*** Each whisker represents about ¼ of the data.
The prices of the watches at a store are summarized
in the box-and-whisker plot below.
a. About what fraction of the watches are on
clearance?
b. About what fraction of the watches are on
sale?
Try these on your own
* Ex. 3: Comparing Box-and-Whisker Plots
The box-and-whisker plots represent the number of
points scored in each game of the 2001–2002 season
for the New England Patriots and the St. Louis
Rams. What conclusions can you make about the
data?
Try these on your own
1. In Example 3, how do the lower extremes of the
points scored compare?p
Guided Practice/Ticket out the Door