1. Lesson 13.7 Interpret Stem-and-Leaf Plots and Histograms
Essential Question: How do you make stem-and-leaf plots and histograms?

2. Before we start…
Group the prices according to the tens digit and complete the table.
The data below shows the prices of 14 brands of jeans. Write the data in numerical order.
25, 35, 29, 18, 20, 40, 26, 28, 33, 30, 39, 42, 38, 26
Tens Digit
Data 1 2 3 4

3. What is a stem-and-leaf plot?
A data display that organizes data based on their digits.
stem (the leading digit(s)) and a leaf (the last digit)
A key that tells you how to read the data.

4. How do you make a stem-and-leaf plot?
Separate the data into stem and leaves.
List the stems in numerical order.
Write the leaves in increasing order.

5. Baseball The number of homeruns hit by the 20 baseball players with the best single season batting averages in Major League Baseball since 1900 are listed below. Make a stem-and-leaf plot of the data.
14, 25, 8, 8, 7, 7, 19, 37, 39, 18, 42, 23, 4, 32, 14, 21, 3, 12, 19, 41

6. U.S. History The years in which each of the first 20 states were admitted to the Union are listed below. Make a stem-and-leaf plot of the years.
1788, 1787, 1788, 1816, 1792, 1812, 1788, 1788, 1817, 1788, 1787, 1788, 1789, 1803, 1787, 1790, 1788, 1796, 1791, 1788

7. Gymnastics The back-to-back stem-and-leaf plot shows the ages of members of the U.S. men’s and women’s 2004 Olympic gymnastics teams. Compare the ages of the gymnasts on the two teams.

8. What is frequency? The number of data values in that interval.
A stem-and-leaf plot shows the frequencies of intervals determined by the stems.

9. What is a frequency table?
Is used to group data values into equal intervals, with no gaps between intervals and no intervals overlapping.

10. What is a histogram?
A bar graph that displays data from a frequency table.
Equal sized bars
Length = frequency
No space

11. How do you make a histogram?
Choose equal intervals that cover all of the data values.
Organize the data using a frequency table.
Use the intervals to draw the bars of the histogram.

12. Make a histogram.
78, 96, 72, 108, 82, 108, 99, 118, 94, 100, 86, 74

13. Make a histogram.
58, 55, 65, 69, 66, 53, 60, 68, 61, 52, 66, 51

14. Books A survey asked people how many books they read in the last month
Books A survey asked people how many books they read in the last month. The results are shown in the table.
Make a histogram of the data. What is the probability that a person surveyed, chosen at random, has read 0 – 5 books in the last month?

15. How do you make stem-and-leaf plots and histograms?

16. Ticket Out the Door
Give a possible key for the stem-and-leaf plot.