Center, Spread, and shape of a date set Ms. Wright asked her 25 students how many books each had read last summer. The smallest
response was 9 books, and the largest was 15 books. The table gives the mean, median
rangs, and interquartile range (IQR) of the data set.
Summary values
Mean
12
Median
12
IOR
Range
6
2
(a) Select the best description of center for the data set.
The average number of books read was about 12,
based on the mean and median.
(b) Select the best description of spread for the data set.
We can tell by the mean that the middle half of the data
set is 12 units wide
The average number of books read was about 25,
which is the number of students in the class.
We can tell by the IQR that the middle half of the data
set is 2 units wide.
O The "average" number of books read was about 2 to 6,
based on the IQR and range.
We can tell by the number of students in the class that
the middle half of the data set is 25 units wide.
(c) Select the graph with the shape that best fits the summary values.
O Graph 1 (The data set is symmetric.)
Graph 2 (The data set is not symmetric.)
Number of students
Number of students
9
15
10 11 12 13 14
Number of books read
7
8 9
10
Number of books read
11