Basic Mathematics for College Students

Read line graphs.

Another type of graph, called a line graph,is used to show how quantities change with
time. From such a graph, we can determine when a quantity is increasing and when it
is decreasing.

The Language of Mathematics The symbol is often used when graphing

to show a break in the scale on an axis. Such a break enables us to omit large

portions of empty space on a graph.

5

7.1 Reading Graphs and Tables 599

b.The phrase from sources other than those listed indicates subtraction. To find the
percent of gold produced by countries that are not listed, we add the
contributions of all the listed sources and subtract that total from 100%.
100% (10% 12% 7% 10% 4% 10% ) 100% 53% 47%
Countries that are not listed in the graph produced 47% of the world’s total
production of gold in 2008.
c.From the graph we see that China produced 12% of the world’s gold in 2008.
To find the number of ounces produced by China (the amount), we use the
method for solving percent problems from Section 6.2.

is of

x  12%  78 Translate to a percent equation.

Now we perform the multiplication on the right side of the equation.

Write 12% as a decimal: 12% = 0.12.

Do the multiplication.

Rounded to the nearest tenth of a million, China produced

9.4 million ounces of gold in 2008.

x9.36

x0.12 78

    

This is the percent sentence.

12% 78? The units are millions of ounces.

What

number

78

 0.12

156

780

9.36

EXAMPLE (^6) AT M s The line graph below shows the number of
automated teller machines (ATMs) in the United States for the years 2000 through

2007. Use the graph to answer the following questions.

a.How many ATMs were there in the United States in 2001?

b.Between which two years was there the greatest increase in the number of ATMs?

c.When did the number of ATMs decrease?

d.Between which two years did the number of ATMs remain about the same?

2000

250

300

350

325

400

2001 2002 2003 2004

Year

2005 2006 2007

Thousands

ATMs in the U.S.

Source: The Federal Reserve and ATM & Debit News

Self Check 6

AT M SRefer to the line graph of

Example 6.

a.Find the increase in the

number of ATMs between

2002 and 2003.

b.How many more ATMs

were there in the United

States in 2007 as compared

to 2000?

Now TryProblems 45, 47, and 51