Ratio, Rate and Proportion

Ratio, Rate and Proportion

A ratio compares quantities in the same units, while a rate compares quantities with different units, such as kilometres per hour. Simplify ratios by dividing every part by the same common factor. In a proportion, two ratios are equivalent; scale both parts by the same multiplier so the comparison stays fair.

Worked example

A recipe uses 2 cups of oats for 3 cups of milk: ratio $2:3$. For 8 cups of oats, multiply both parts by 4, so use 12 cups of milk.

Exam method

1. Put quantities in the same unit when needed. 2. Write ratio in the stated order. 3. Simplify or scale every part by the same factor.