1. 12.2 Stem-and-Leaf Plots, Histograms, and Circle Graphs
Objectives: Make a stem-and-leaf plot, a histogram, or a
circle graph for a data set.
Find and use relative frequencies to solve
probability problems.
Standards: A Organize and display data using pictures, tallies, tables, charts, bar
and circle graphs E Analyze and display data in a stem-and-leaf plot.

2. I. A stem-and-leaf plot of the Internet data is shown below.
A stem-and-leaf plot is
a quick way to arrange a set of data
and view its shape, or general distribution.
In a stem-and-leaf plot
each data value is split into 2 parts: a stem and leaf.

3. *Ex 1. Colby is planning the annual Smith family reunion.
She has collected the ages of the family members who plan to attend.
a). Make a stem-and-leaf plot of the ages.
b). Find the median and mode of the ages.
c). How can the stem-and-leaf plots be used to plan the reunion?
Stem
Leaf 1 2 3 4 5 6 7 8 9

4. *Ex2. A bakery collected the following data about the
# of loaves of bread sold each of the 24 business days:
53, 49, 27, 48, 60, 52, 44, 38, 47, 52, 82,46, 55,
31, 39, 54, 51, 47, 50, 45, 50, 61, 43, and 64.
Make a stem-and-leaf plot of the data.
Find the median and mode(s) of the data.
How can the owner use the stem-and-leaf plot
to make plans for baking bread?
Stem
Leaf

5. Histogram – a bar graph that gives the frequency of each
value. In a histogram, the horizontal axis
is like a number line
divided into equal widths. Each width represents
a data value or range of data values.
The height of each bar indicates the frequency of
that data value or range of data values.

7. *Ex 2. The given data shows the # of people in 24 vehicles
hat passed a designated checkpoint.
1, 4, 1, 2, 2, 1, 3, 1, 3, 2, 2, 6,
4, 2, 1, 1, 2, 4, 3, 1, 2, 4, 2, 3.
Make a frequency table for these data.
Make a histogram from the frequency table. #
Frequency 1 2 3 4 5 6

8. Relative Frequency Tables –
frequency tables that include a column that displays
how frequently a value appears relative to the entire data set.
The relative frequency
column is the % frequency, or probability.
A relative frequency table and histogram are
shown below for the canoe rental data.

9. *Ex1. Use the relative frequencies given above
to estimate the probability that randomly selected
customer will rent a canoe for 5 or more hours.
What % rented a canoe for 5, 6, 7, and 8 hours?

10. display the distribution of non-overlapping parts of a whole
Circle Graphs –
display the distribution of
non-overlapping parts of a whole

12. *Ex 2. The table below shows the distribution
by region of the resident population of the
U.S. in 1996.
a). Make a circle graph to represent the data.
b). Find the probability that a randomly chosen
resident of the U.S. in 1996 wasn’t a
resident of the South.
Region
Population
(In millions)
Relative Frequency NE
51.6
Midwest
62.1
Sout
93.1
West
58.5

14. Writing Activities

15. Review of Stem-and-Leaf Plots, Histograms, and Circle Graphs