Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall. 6.4 Solving Percent Problems with Proportions
Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall. 6.4 Solving Percent Problems with Proportions.
Dec 22, 2015
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Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall.
6.4
Solving Percent Problems with
Proportions
Martin-Gay, Prealgebra & Introductory Algebra, 3ed 22
Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall.
To understand the proportion method, recall that
30% means the ratio of 30 to 100, or .
Writing Percent Problems as Proportions
30
100
30 3
30%100 10
Martin-Gay, Prealgebra & Introductory Algebra, 3ed 33
Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall.
Since the ratio is equal to the ratio , we
have the proportion
called the percent proportion.
Writing Percent Problems as Proportions
,,
30
1003
10
30 3
100 10
Martin-Gay, Prealgebra & Introductory Algebra, 3ed 44
Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall.
always 100
or
percent
base
amount
Percent Proportion
amount percent
base 100
100
a p
b
Martin-Gay, Prealgebra & Introductory Algebra, 3ed 55
Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall.
When we translate percent problems to proportions, the percent, p, can be identified by looking for the symbol % or the word percent. The base, b, usually follows the word of. The amount, a, is the part compared to the whole.
Symbols and Key Words
Martin-Gay, Prealgebra & Introductory Algebra, 3ed 66
Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall.
Part of Proportion How It’s Identified
Percent % or percent
Base
Amount
Appears after of
Part compared to whole
Helpful Hints
Martin-Gay, Prealgebra & Introductory Algebra, 3ed 77
Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall.
What number is 20% of 8?
amount percent base
amount
base
percent
Solving Percent Proportions for the Amount
20
8 100
a
Martin-Gay, Prealgebra & Introductory Algebra, 3ed 88
Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall.
20 is 40% of what number?
amount percent base
amount
base
percent
20 40
100b
Solving Percent Proportions for the Base
Martin-Gay, Prealgebra & Introductory Algebra, 3ed 99
Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall.
What percent of 40 is 8?
amountpercent base
amount
base
percent
8
40 100
p
Helpful HintHelpful HintRecall from our percent proportion that this number, p already is a percent. Just keep the number the same and attach a % symbol.Recall from our percent proportion that this number, p already is a percent. Just keep the number the same and attach a % symbol.
Solving Percent Proportions for the Percent
Martin-Gay, Prealgebra & Introductory Algebra, 3ed 1010
Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall.
A ratio in a proportion may be simplified before
solving the proportion. The unknown number in
both
and
is 20.
6 30
4 b
3 30
2 b
Helpful Hint
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