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: 2.6.5A Organize and display data using pictures, tallies, tables, charts, bar and circle graphs. 2.6.8E Analyze and display data in a stem-and-leaf plot.

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.

*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

*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

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.

*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

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.

*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?

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

*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

Writing Activities

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