In this Grade 4 AMC Math lesson from The Art of Problem Solving: Prealgebra, students learn how to identify and solve proportions by setting up equal ratios between two related quantities. Using problems drawn from real-world contexts such as currency exchange rates, recipe scaling, shadow lengths, and map scales, students practice writing proportion equations and solving for unknown values with cross-multiplication and scaling methods. This lesson is part of Chapter 7 on Ratios, Conversions, and Rates and builds foundational skills for recognizing when two quantities are proportional.
Section 1
Proportions
A proportion is a statement that two ratios are equal. For example, .
If , then , as long as . This shortcut is known as cross-multiplying.
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Section 1
Proportions
A proportion is a statement that two ratios are equal. For example, .
If , then , as long as . This shortcut is known as cross-multiplying.
Book overview
Jump across lessons in the current chapter without opening the full course modal.
Continue this chapter