Solving Percent Problems with Proportions

1
Solving Percent Problems with Proportions
Section 7.3
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Writing Percent Problems as Proportions
To understand the proportion method, recall that
30 means the ratio of 30 to 100, or .
30
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Writing Percent Problems as Proportions . . .
Since the ratio is equal to the ratio
, we have the proportion
,
called the percent proportion.
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Percent Proportion
always 100
or
percent
amount
base
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When we translate percent problems to
proportions, the percent can be identified by
looking for the symbol or the word percent. The
base usually follows the word of. The amount is
the part compared to the whole.
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Helpful Hint
Part of Proportion
How Its Identified
Percent
or percent
Base
Appears after of
Amount
Part compared to whole
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Solving Percent Proportions for the Amount
What number is 20 of 8?
amount
percent
base
amount
percent
base
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Solving Percent Proportions for the Base
20 is 40 of what number?
amount
percent
base
amount
percent
base
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Solving Percent Proportions for the Percent
What percent of 40 is 8?
amount
percent
base
amount
percent
base
10
Helpful Hint
A ratio in a proportion may be simplified before
solving the proportion. The unknown number in
both and
is 20.
Martin-Gay, Prealgebra, 5ed