Proportions for ProsHonors Math/3rd Period

Ms. Shelly Brown-Jones 7-5

Presented by Justice Adams

• To define a proportion and its parts and terms.

• To exemplify the method of determining what constitutes a proportion and what does not (and to establish proportion to find missing terms).

• To demonstrate examples of proportions and non-proportions.

Objective

Defining a Proportion

•  mm

Showing Ratios

• 1 boy for every 3 girls = 1:3

• ¼ boys ¾ girls (a whole equals 4/4)

• 25% or 0.25 are boys (divide 1 by 4)

The Parts and Terms of a Proportion

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Testing Proportions

• Cross products are used to test whether two ratios are equal and form a proportion. • Cross products are determined by simply cross-

multiplying a given pair of ratios.• An equal (=) or not equal sign (≠) is used to

correspond with whether or not the products are equal or are a proportion.

Examples

Finding Missing Terms in a Proportion

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Word Problems Using Proportions 

Proportion Quiz

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Proportion Quiz Answers

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Summary

• A proportion exists when two ratios are equal. Whether a pair of ratios is equal or not equal is determined by multiplying extremes by means or cross-multiplying the given set of fractions. Cross products and other methods are also used to solve word problems using proportions, and generally to find a missing term in a proportion.

Resources

Online Math Assistance

• Visit www.math.com or www.mathisfun.com for assistance with proportions and other math problems.

Typing Equations 1. To type an equation in PowerPoint (or Microsoft Word) click the

“Insert” tab at the top of the screen and then the “Equation” icon.

2. Type what you would like to be converted into a proper equation into the equation box (type the forward slash / between the numbers, without spaces, to get a proper fraction).

3. Click enter.

Typing Mathematical Symbols• To type mathematical symbols, like the “not equal to” sign (≠), etc., click

the “Insert” tab and then “Symbol” to select the appropriate symbol. Click insert.