SAT and ACT math terms · SAT Math, ACT Math
Ratio and proportion
Ratio and proportion: A ratio compares two quantities; a proportion states that two ratios are equal.
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What it means
Ratios can be written as a:b or a/b. Proportions are solved by cross-multiplying. Rates are ratios with units, such as miles per hour, and unit conversions use ratios equal to 1.
Watch whether a ratio compares part to part or part to whole.
Example
If the ratio of boys to girls is 3:5 in a class of 32, there are 3/8 × 32 = 12 boys and 20 girls.
On the exam
Ratios, rates and unit conversions are frequent on both tests, often embedded in multi-step word problems.