Pre-Algebra

Pre-Algebra introduces foundational concepts in mathematics, including integers, fractions, and basic equations, essential for higher-level math courses.

Advanced Topics

Ratios and Proportions

What Is a Ratio?

A ratio shows how two numbers compare. It tells us how much of one thing there is compared to another.

What Is a Proportion?

A proportion says that two ratios are equal. It's a way to solve problems where things change at the same rate.

How to Write Ratios

  • With a colon: 2:3
  • As a fraction: \( \frac{2}{3} \)

Solving Proportions

If \( \frac{a}{b} = \frac{c}{d} \), then \( a \times d = b \times c \).

Why Use Ratios and Proportions?

Recipes, maps, and models all use ratios so things stay in balance!

Fun Fact

Artists use proportions to draw realistic faces and bodies.

Examples

  • If a recipe calls for 2 cups of flour and 3 cups of sugar, the ratio is 2:3.

  • If 5 pencils cost $2.50, 10 pencils cost $5.00 (the proportion stays the same).

In a Nutshell

Ratios compare two numbers; proportions show that two ratios are equal.