Define Proportions

What is a proportion?

An equation that states two ratios are equal.

What are cross products?

A method used to check if two ratios are equal.

How do you find equivalent fractions?

Multiply or divide the numerator and denominator by the same number.

How do you test using cross products?

Multiply numerator of one × denominator of the other, then compare with the other pair.

When do ratios form a proportion?

When the cross products are equal.

Example: Are 4/5 and 20/25 proportional using equivalent fractions?

Yes, both equal 20/25.

Example: Are 4/5 and 20/25 proportional using cross products?

4 × 25 = 100 and 5 × 20 = 100, so yes.

Final answer: Do 4/5 and 20/25 form a proportion?

Yes, they are proportional.

Quick tip to remember proportions

If cross products are equal → it’s a proportion.