Download Writing Decimals as Percents

Math 300
Basic College Mathematics
Chapter 6
Percent
Math 300 M-G 4e Chapter 6; Rev: Mar 2011
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6.1 Introduction to Percent
 The root word “cent” means “hundred”. Therefore, the notation n%
n
(read “n percent”) means “n per hundred” or the ratio:
100
1. In a survey of 100 people, 54 preferred chocolate syrup on their ice cream.
What percent preferred chocolate syrup?
Dr. Pepper:
DP
When changing from a decimal to a percent,
move decimal point 2 places → (right), and put in a % sign.
When changing from a percent to a decimal,
move decimal point 2 places ← (left), and remove % sign.
Writing Percents as Decimals
Examples: Write each percent as a decimal.
2. 64%
3. 52.7%
4. 1.7%
Writing Decimals as Percents
Examples: Write each decimal as a percent.
5. 0.75
6. 4.8
7. 56
8. 0.006
Math 300 M-G 4e Chapter 6; Rev: Mar 2011
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6.2 Percents and Fractions
Writing Percents as Fractions
 To write a percent as a fraction,
n
a. Replace the n % with
(fraction equivalent).
100
b. Always remember to simplify, if possible.
Note: There may be cases where the numerator will contain a decimal. If so, you
will need to multiply both numerator and denominator by a 10, 100, 1000, etc.
in order to move the decimal to the far right (add zeroes as necessary).
Example: Write each percent as a fraction or mixed number in simplest form.
1. 24%
2. 250%
3. 62.5%
Math 300 M-G 4e Chapter 6; Rev: Mar 2011
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6.2 Percents and Fractions (cont)
Writing Fractions as Percents
 To write a fraction as a percent,
a. Divide numerator by denominator on calculator: top ÷ bottom
b. By hand, change the decimal to a percent using “Dr. Pepper.”
Note: If applicable, change Mixed Numbers to Improper Fractions first.
Example: Find percent notation.
1.
73
100
2.
3
10
3.
5
8
4. 2
1
5
Math 300 M-G 4e Chapter 6; Rev: Mar 2011
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Math 300 Chapter 6
Glossary
Percent – per 100. The symbol % is used to denote percent.
Properties
To convert from a percent to a decimal, we drop the % symbol and
multiply by 0.01
To convert from a percent to a fraction, we drop the % symbol and
multiply by 1/100.
Hints
Percent -> Remove % symbol and move decimal point 2 places to the
left -> Decimal
Percent <- move the decimal point to places to the right and attach the
% symbol <- Decimal
Zeros often need to be added as a place holder during conversion
100% = 1
Percent to decimal - p%=p(0.01)
Percent to fraction – p% = p(1/100)
Number as a percent – n = n (100%)
Percent equations = Percent (base) = amount
When solving a percent equation, write the percent as a decimal or
fraction then solve the problem.
When solving for percent, don’t forget to convert you answer to a
percent (from a decimal or fraction).
100% of a number = number
Percent greater than 100%, answer will be larger than original number
Percent less than 100%, answer will be less than the original number
Math 300 M-G 4e Chapter 6; Rev: Mar 2011
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