Functions and Proportional Relationships

A proportional relationship is a relationship between two quantities where the ratio of one quantity to the other quantity is constant.

A relationship is proportional if the graph is a straight line that passes through the origin (0,0).

A relationship varies directly when one quantity increases or decreases in direct proportion to another quantity.

Divide her earnings by the number of hours: $187.15 ÷ 19 = $9.85 per hour.

Speed = Distance ÷ Time.

Her speed is 65 miles per hour (260 miles ÷ 4 hours).

A function is a relation where each input has exactly one output.

A mapping is a function if no input is paired with more than one output.

If a graph does not touch the origin, it indicates a non-proportional relationship.

$308 (Set up a proportion: 70/5 = x/22).