How to Calculate Ratio

What is Ratio?

A ratio compares two or more quantities of the same kind. Written as a:b or a/b. Ratios are used in recipes (3:1 flour to water), maps (1:50,000), financial analysis (P/E ratio), and mixing (2-stroke fuel). A proportion is an equation stating two ratios are equal.

Step-by-Step Guide

1. 1Simplify by dividing by GCF: 12:8 = 3:2
2. 2Part-to-part: ratio of boys to girls in a class
3. 3Part-to-whole: boys to total students (gives fraction/percentage)
4. 4Proportion: if a/b = c/d, then ad = bc (cross multiplication)

Worked Examples