FTCE General Knowledge Math Practice Test

What is an equation where one fraction is set equal to another, often solved by cross multiplication?

1. Ratio

2. Equation

3. Proportion

4. Identity

The correct answer is: Proportion

A proportion is a specific type of equation that expresses the equality of two ratios. When written in the form of a fraction set equal to another fraction, such as \( \frac{a}{b} = \frac{c}{d} \), it can be solved using cross multiplication, which involves multiplying the numerator of one fraction by the denominator of the other and setting the resulting products equal to each other, \( a \times d = b \times c \). This method provides a straightforward way to find unknown values in the relationship defined by the proportion. Understanding this concept is crucial for solving various mathematical problems, particularly those involving ratios and scaling. While an equation can represent any mathematical statement that asserts the equality of two expressions, a proportion specifically refers to those cases involving fractions or ratios. Ratios themselves indicate a relationship between two quantities but do not necessarily imply equality. An identity, on the other hand, is an equation that holds true for all values of the variable involved, which is a different concept altogether.