Fundamentals of Mathematics, 2008a

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7.3 Proportions 3
7.3.1 Section Overview
• Ratios, Rates, and Proportions
• Finding the Missing Factor in a Proportion
• Proportions Involving Rates
7.3.2 Ratios, Rates, and Proportions
Ratio, Rate
We have dened a ratio as a comparison, by division, of two pure numbers or two like denominate numbers.
We have dened a rate as a comparison, by division, of two unlike denominate numbers.
Proportion
A proportion is a statement that two ratios or rates are equal. The following two examples show how to
read proportions.
7.3.2.1 Sample Set A
Write or read each proportion.
Example 7.9
3
5 = 12
20
3 is to 5 as 12 is to 20
Example 7.10
10 items
5 dollars = 2 items
1 dollar
10 items is to 5 dollars as 2 items is to 1 dollar
Example 7.11
8 is to 12 as 16 is to 24.
8
12 = 16
24
Example 7.12
50 milligrams of vitamin C is to 1 tablet as 300 milligrams of vitamin C is to 6 tablets.
50
1 = 300
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