Percentage questions test your understanding of ratios and how to convert between part-to-whole relationships. This guide provides fool-proof strategies to solve these problems.
Percentages are a fundamental concept in math, representing a part-to-whole relationship out of 100. On the Digital SAT, these questions show up on almost every single exam. The term "percent" means "per hundred." For example, 25% means 25 out of 100.
Calculate Percentages
To calculate a percentage, use the formula: Percentage = (Part / Whole) x 100.
Finding a Percentage
Example: 18 out of 20 correct: (18/20) x 100 = 90%. Another: 45 out of 60 apples: (45/60) x 100 = 75%.
Finding Complementary Percentages
If 30% are blue, then 70% must be red. A store sold 40% of 200 items. Unsold: (60/100) x 200 = 120 items.
Complete Example
Problem: 60% of juniors played sports. If 300 played, how many in the class? Solution: 300 = 0.60 x Whole, so Whole = 500.
Switch Between Equivalent Forms
Percentages can be expressed as fractions or decimals. For example, 25% = 0.25 = 1/4.
Converting Percentages
To decimal: move decimal two places left. To fraction: write over 100 and simplify.