What is a proportion?

What is a proportion?

• A. A ratio plus a ratio.
• B. 2 ratios set equal to each other.
• C. The slope form of a line.
• D. A function's input-output pair.

Answer: (B)

A proportion expresses that two ratios describe the same relationship, written as one ratio equal to another. For example, 3/4 = 6/8 shows the same portion of a whole in two different contexts. You can check it by cross-multiplying: 3 × 8 equals 4 × 6, so the two ratios truly match. This idea—two ratios being equal—captures the constant relationship that a proportion conveys. Adding two ratios isn’t what a proportion does, so that choice isn’t right. The slope form of a line describes how y changes with x, not an equality of two separate ratios. A function’s input-output pair describes a single mapping from input to output, not a statement about two ratios having the same relation.

A proportion expresses that two ratios describe the same relationship, written as one ratio equal to another. For example, 3/4 = 6/8 shows the same portion of a whole in two different contexts. You can check it by cross-multiplying: 3 × 8 equals 4 × 6, so the two ratios truly match. This idea—two ratios being equal—captures the constant relationship that a proportion conveys.

Adding two ratios isn’t what a proportion does, so that choice isn’t right. The slope form of a line describes how y changes with x, not an equality of two separate ratios. A function’s input-output pair describes a single mapping from input to output, not a statement about two ratios having the same relation.