Chapter 10 Math 279
Example: Grace is in a health occupations class. There are 35
students in the class. A high percentage of the students are inter-
ested in a nursing career. The total number of students interested
in a nursing career is 28, representing 80% of the students. The
calculation to establish this percentage is: 28 ÷ 35 = .80, or 80%.
Converting a Percentage to a Decimal Fraction
To convert a percentage into a decimal fraction, you must divide by 100
or move the decimal point two places to the left and drop the percent sign.
Examples: 14% = 14.0 = 0.14
29.9% = 0.299
In the same manner, a decimal fraction can be converted to a percent-
age by multiplying by 100, or by moving the decimal point two places to
the right and adding a percent sign.
Percentages are often used in your daily life. For example, you are
charged a sales tax on every purchase you make. The sales tax is always
a percentage of the total bill. You will also see percentages used during
department store sales. The sale price represents a percentage of the origi-
nal price (Figure 10.6).
Examples: 0.41 = 41%
0.042 = 4.2%
Using Percentages
1. A box of table salt (sodium chloride) is comprised of 40% sodium. If a
box of salt weighs 26 ounces, how many ounces of sodium are in the box
of salt?
2. 30 people at Eastridge Hospital had surgery on May 21st—4 were chil-
dren, 12 were men, and 14 were women. What percentage of the people
who received surgery on May 21st were children?
3. Dr. Levin, an orthopedist, has 36 patients who suffer from osteoporosis.
This condition causes the bones to become brittle and break more eas-
ily than healthy bones. This year, 15 patients had broken hips, 11 had
collapsing vertebrae, and 10 had broken wrists. What percentage of
Dr. Levin’s osteoporosis patients had broken hips this year?
Real Life Scenario
Fractions, Decimals, and Percentages
Fraction Decimal Percentages
3/20 0.15 15%
1/5 0.20 20%
5¼ 5.25 525%
Figure 10.5 Moving from fractions to decimals and percentages provides a variety of
ways to express numbers less than 1.
Think It Through
If you have a credit card,
and you do not pay off
your balance, or total,
every month, what per-
centage does the credit
card company charge
you as interest on the
unpaid amount?
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Figure 10.6 Percentages are
often used in department store
sales.