Direct variation

​Lesson 8.4

Direct variation

Multiple Choice

The cost y of movie tickets varies directly with the number of tickets x as shown in the graph.

 

 

Write a direct variation equation in the form y = kx to represent this relationship.

• Y=16x

• x=8y

• Y=8x

• Y=x

​The constant of variation is 8 . This means that the cost per ticket is $ 8 .

Multiple Choice

Write a direct variation equation to represent the relationship.

• y=3x

• y=195x

• X=65y

• y=65x

​The constant of variation is 65 . This means that the number of miles per hour is 65.

Multiple Choice

The cost of paper y varies directly with the number of reams bought x. Suppose two reams cost $5.10.

 

Write a direct variation equation in the form y = kx to represent this relationship. Express the constant of variation as a decimal.

• y=5.10x

• y=2.55x

• y=2x

• y=10.20x

​The constant of variation is 2.55 . This means that the cost per ream is $2.55.

Multiple Choice

The amount of flour needed for a recipe y varies directly with the number of servings planned x. Three servings require 4.5 cups of flour.

Write a direct variation equation in the form y = kx to represent this relationship.

• y=1.5x

• y=4.5x

• Y=13.5x

• x=1.5y

​The constant of variation is 1.5

This means that each serving requires 1.5 cup(s) of flour.