Master essential math concepts and problem-solving skills tested on the New SAT without the use of a calculator.
Ratios, proportions, and percents help us compare numbers and understand parts of a whole—a frequent SAT topic.
A ratio compares two quantities, written as \( a:b \) or \( \frac{a}{b} \).
A proportion states that two ratios are equal: \( \frac{a}{b} = \frac{c}{d} \). Solve by cross-multiplying.
Percents are ratios out of 100. To find a percent, use \( \frac{\text{part}}{\text{whole}} \times 100 \).
These concepts appear in discounts, recipes, and even map reading!
If a recipe calls for 2:3 sugar to flour, doubling means 4:6.
What is 30% of 50? \( 0.3 \times 50 = 15 \).
Use ratios, proportions, and percents to compare, scale, and solve everyday math problems.