Basic Mathematics for College Students

Caution! One drawback of a pictograph is that it can be

difficult to determine what fractional amount is represented

by a portion of a symbol. For example, if the CD shown to

the right represents 1,000 units sold, we can only estimate

that the partial CD symbol represents about 600 units sold.

Read circle graphs.

In a circle graph, regions called sectorsare used to show what part of the whole each

quantity represents.

The Language of Mathematics A sectorhas the shape of a slice of pizza or a

slice of pie. Thus, circle graphs are also called pie charts.

4

 1,000 units

 600 units

598 Chapter 7 Graphs and Statistics

StrategyWe will count the number of complete pizza symbols that appear in the

top row of the graph, and we will estimate what fractional part of a pizza symbol

also appears in that row.

WHYThe key indicates that each complete pizza symbol represents one dozen

(12) pizzas.

Solution

The top row contains 3 complete pizza symbols and what appears to be of

another. This means that the men’s residence hall ordered , or 36 pizzas, plus

approximately of 12, or about 3 pizzas. This totals 39 pizzas.^14

3  12

1

4

EXAMPLE (^5) Gold Production The
circle graph to the right gives information about
world gold production.The entire circle represents
the world’s total production of 78 million troy
ounces in 2008. Use the graph to answer the
following questions.
a.What percent of the total was the
combined production of the United
States and Canada?
b.What percent of the total production
came from sources other than those
listed?
c. To the nearest tenth of a million, how
many ounces of gold did China produce
in 2008?
StrategyWe will look for the key words in each problem.
WHYKey words tell us what operation (addition, subtraction, multiplication, or
division) must be performed to answer each question.
Solution
a.The key word combinedindicates addition. According to the graph, the United
States produced 10% and Canada produced 4% of the total amount of gold in

2008. Together, they produced 10%4%, or 14% of the total.

U.S.

10%

Other

SouthAfrica

10%

China 12%

Canada

4%

Australia

10%

Russia

7%

2008 World Gold Production

78 million troy ounces

Source: Goldsheet Mining Directory

Self Check 5

GOLD PRODUCTIONRefer to the

circle graph of Example 5. To the

nearest tenth of a million, how

many ounces of gold did Russia

produce in 2008?

Now TryProblems 37, 41, and 43