7th Grade Math

Lesson 3E Statistical Displays 531

Stem-and-Leaf Plots

More

AboutAbout

A back-to-back stem-and-leaf plot uses one stem to compare two sets

of data.

FOOTBALL Refer to the back-to-back stem-and-leaf plot below.

The leaves for

one set of the

data are on one

side of the stem.

Fantasy Football Points

Eagles’ Kicker Stem Titans’ Kicker

9 8 8 8 7 7 7 5 3 1

6 4 4 3 2 2

0

1

0 3 4 5 6 6 7 7 7 7

0 1 2 2 3 7

(^2) | 1 = 12 points (^1) | 7 = 17 points
The leaves for the
other set of data
are on the other
side of the stem.
a. Which team’s kicker had a greater range of points?
The range for the Eagles’ kicker is 16 - 1 or 15.
The range for the Titans’ kicker is 17 - 0 or 17.
Since 17 > 15, the Titans’ kicker had a greater range of points.
b. Which team’s kicker scored 11 or more points a greater number of times?
The Eagles’ kicker scored 11 or more points 6 times.
The Titans’ kicker scored 11 or more points 5 times.
So, the Eagles’ kicker scored 11 or more points a greater number
of times.
SCORES The quiz scores of two English classes are shown in English Quiz Scores
Class A Stem Class B
9 8
9 8 6 4 2 2
8 6 5 1
4 3 0
6
7
8
9
4 7 9
1 7 9 9
0 1 2 3 5 6
1 2
(^8) | 6 = 68% (^6) | 4 = 64%
the back-to-back stem-and-leaf plot.

19. Which measure(s) of central tendency would students in
    Class B want to use to show that they performed better on
    the quiz?


20. Which class has a greater range of scores? Explain.


21. Based on the data, can you conclude that Class A has the better English
    quiz scores? Explain your reasoning.


22. Write a sentence that compares the data.

SANDWICHES The back-to-back stem-and-leaf plot shows Fat (g) of Various Burgers

and Chicken Sandwiches

Chicken Stem Burgers

8

9 8 5 5 3 3

0

0

1

2

3

0 5 9

0 6

0 3 6

8 | 0 = 8 g 2 | 6 = 26 g

nutrition information about sandwiches.

23. What is the greatest number of fat grams in
    each sandwich?


24. Compare the median number of fat grams for
    each sandwich.


25. In general, which type of sandwich has a lower amount
    of fat? Explain.


26. Write a sentence that describes the data.

513_531_C09_L3_895130.indd 531 1/11/10 9:41 AM