Chapter 10 Statistical Measures and Displays
Lesson 10-4 Dot Plots
Page 811
The following data represent the length of several summer camps in days:
7, 7, 12, 10, 5, 10, 5, 7, 10, 9, 7, 9, 6, 10, 5, 8, 7, and 8. Represent the set of
data in a dot plot. Determine the median, mode, range, and any outliers.
Then interpret the data by describing the center and spread.
To make a dot plot, place as many dots above each number as there are
responses for that number. Include a title.
Median: Order the data from least to greatest.
5, 5, 5, 6, 7, 7, 7, 7, 7, 8, 8, 9, 9, 10, 10, 10, 10, 12
The median is 7.5 because it is the mean of 7 and 8, the middle values of the
data set.
Mode: The data value 7 appears more often in the data set than any other
number. So, the mode is 7.
Range: The greatest value is 12 and the least value is 5. So, the range is 12 − 5
or 7.
Outlier: The limits for the outlier are 2.5 and 14.5. Since there are no data
values beyond the limits, there are no outliers in the data set.
There are a total of 18 summer camps represented. The median means that onehalf of the summer camps are longer than 7.5 days and one-half are less. More
camps are 7 days than any other number of days.
Texas Math, Course 1
The dot plot shows the number of songs in play lists. Describe the center
and spread of data.
Sample answer: There are 15 play lists represented.
Mean:
25  36  38  38  39  39  40  40  40  42  42  42  45  47  47
 40
15
Median: 25, 36, 38, 38, 39, 39, 40, 40, 40, 42, 42, 42, 45, 47, 47
The median is 40 because it is the middle value of the data set.
Mode: The numbers 40 and 42 appear three times in the data set. The modes
are 40 and 42 songs.
So, the majority of the data is close to the measures of center.
Q1: The data values in the first quartile are: 25, 36, 38, 38, 39, 39, 40
The median of this data set is 38. So the first quartile is 38.
Q3: The data values in the third quartile are: 40, 42, 42, 42, 45, 47, 47
The median of this data set is 42. So the third quartile is 42.
IQR: Subtract the first quartile from the third quartile to find the interquartile
range. 42 − 38 = 4
An interquartile range of 4 means half the playlists have between 38 and 42
songs.
Outlier: There is an outlier at 25.
Texas Math, Course 1