Thi nk^
What must be the
same in order to
compare the shapes
of the line plots?
The intervals on the
number line must be
exactly the same.
& G o t It? 4. The line plot shows the number of students in each
homeroom at Jefferson High School.
a. Find the mean, median, and range of the data.
b. How can you use the line plot to determine
whether the mean and median are equal?Number of Students
XX
X
X
XX
X
X
X
XX
X
X
X
XX
XX
X
19 20 21 22 23 24Comparing Measures of Central TendencyThe results from the same quiz given to two different classes are shown in the line plots.Cl ass A Cl ass B
XX XX
XX XXX
XXXX XXX
X XXXXX XXX
XXXXXX XXXX
XXXXXX XXX XXX(^1234561 2 3456)
Quiz Scores Quiz Sco res
0 Which class has a higher standard for being in the top half of the quiz scores?
In order to be in the top half of the quiz scores, a student must have a greater quiz
score than 50% of the class. The median is the middle value, therefore 50% of the data
are less than the median and 50% of the data are greater than the median. You need to
calculate the median of each data set to determine which class has a higher standard
for being in the top half of the quiz scores.
Class A:
^ 4- 4 7
Median: ^ — 3.5
Class B:
Median: 5
Class B has a higher standard for being in the top half of the quiz scores.
0 By comparing line plots, how can you tell which mean is greater?
The data for Class B are shifted right when compared to the
data for Class A. Therefore the mean will be greater. Cl ass C
- G o t It? 5. Results from a third class are shown here.
a. Is the mean for Class C greater than or less than the
mean for Class A?
b. Is the median for Class C greater than or less than
the median for Class A?
c. How can you tell which data set has a greater mean
by comparing the graphs?
X X X X X X
X
X
X
X
X
X
X
X
X
2 3 4 5
Qui z Sco r es
X
X
X
X
X
Po w erAlg eb ra.com [Tesson 12-3 M easures o f Cen t r al Tend ency and Dispersion 741