Bell Quiz

Objectives• Interpret various data displays, including

double-bar graphs, stem-and-leaf plots, double-line graphs, and circle graphs.

New Concepts • Numerical data can be displayed in

different ways. • Bar graphs use vertical and horizontal

bars to represent data. • A Double-Bar Graph shows groups of two

bars side by side.– This allows easier comparison of two

related sets of data.

Example 1Interpreting Double-Bar Graphs

Sal and Harry both own sandwich shops. The double-bar graph shows the number of shops they owned at the end of each year. What conclusions can be made from the graph?

Lesson PracticeWhat year show the greatest difference between the number of shops Sal and Harry owned?

Stem-and-Leaf Plot• A Stem-and-Leaf Plot is a data display

that uses some digits as “stems” and others as “leaves”.

• The “stems” have a greater place value than the “leaves”.

• Stem-and-leaf plots are useful for organizing and ordering data.

Example 2Interpreting Stem-and-Leaf Plots

• The stem-and-leaf plot shows the ages of members of a hiking club.

• Find the age of members at the hiking club that occurs most often.

Lesson PracticeMake a stem-and-leaf plot of the data showing the height in inches of grandchildren in the Jackson family: 56, 52, 68, 49, 49, 40, 72, 71, 43, 54. What height occurs most often?

Line Graphs• In a Line Graph, a line is drawn through

points on a grid to show trends and changes in data over time.

• As with bar graphs, two related data sets can be compared in a Double-Line Graph.

Example 3 Solving Equations by Dividing

The double-line graph shows the same data as the double-bar graph in Example 1.

What conclusion can you make from the graph?

Lesson PracticeWhat was the greatest number of shops Sal opened in one year?

Example 4 Comparing Data using Double-Bar Graphs

The table shows Andre’s bank account transactions. Make a graph to compare the deposits and withdrawals.

Example 4 Comparing Data using Double-Bar Graphs

Solution:

Lesson PracticeWhich month shows the greatest difference between deposits and withdrawals.

Example 5Solving Equations by Dividing

The circle graph shows Art Online’s total yearly sales by quarter. The total amount of sales for the year was $20 million. Find the sales for each quarter.

Lesson Practice

If first quarter sales the next year are $3,000,000, predict the total sales for the year.