AFOQT Practice Test

Which equation represents an inversely proportional relationship?

1. y = kx

2. y = 60/x

3. y = x^2

4. y = ax + b

The correct answer is: y = 60/x

The equation that represents an inversely proportional relationship is indeed the one formatted as y = k/x (which is structurally the same as y = 60/x). In inverse proportionality, as one variable increases, the other variable decreases, and their product remains constant. In this case, 60 is the constant \( k \). When you analyze this equation, for example, if y equals 60 when x is 1, then if x is increased to 2, y would decrease to 30, demonstrating the relationship between the two variables. This behavior illustrates how they are inversely related. The other options represent different types of relationships: the first option describes a direct proportional relationship (y increases as x increases), the third option portrays a quadratic relationship where y increases at an accelerating rate as x increases, and the fourth option defines a linear relationship which consists of a slope and y-intercept. None of these depict an inverse relationship like the correct option does.