Introducing Proportional Relationships

A recipe for salad dressing calls for 3 tablespoons of oil for every 2 tablespoons of vinegar. The line represents the relationship between the amount of oil and the amount of vinegar needed to make salad dressing according to this recipe. The point (1, 1.5) is on the line. Label the vertical axis (BLUE box).

• Oil (tablespoons)

• Vinegar (tablespoons)

If there is a positive constant k so that the quantities x and y are related by the equation y=kx, then we say that y and x are in a _____ relationship.

• complicated

• equivalent

• proportional

• scale

In the equation y=kx, the term k is called the...

• equivalent ratio

• constant of proportionality

• cult of personality

• scale drawing

Which graph represents a proportional relationship?

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Answer explanation

The graph should be a straight line through the origin (0,0).

Andre rode his bike at a constant speed. He rode 1 mile in 5 minutes. Which of these equations represents the amount of time t (in minutes) that it takes him to ride a distance of d miles?

Answer explanation

The amount of time traveled is proportional to the distance. Multiply distance by pace (in miles per minute) to get total time.

Explain how you know which container is filling more quickly.

Answer explanation

The container that is filling more quickly is the one for which the graph is steeper.

A recipe for salad dressing calls for 3 tablespoons of oil for every 2 tablespoons of vinegar. The line represents the relationship between the amount of oil and the amount of vinegar needed to make salad dressing according to this recipe. The point (1, 1.5) is on the line. Label the horizontal axis (RED box).

• Oil (tablespoons)

• Vinegar (tablespoons)

A recipe for salad dressing calls for 3 tablespoons of oil for every 2 tablespoons of vinegar.

Write an equation that represents the proportional relationship between oil, o, and vinegar, v.

Does this graph represent a proportional relationship?

• Yes, it is a straight line and goes through the origin.

• Yes, it is a line that does not go through the origin.

• No, it is not a straight line.

• No, it is a straight line and does not go through the origin.

The graph shows the cost C in dollars of w pounds of blueberries, a proportional relationship. Select all the true statements.

• 1 pound of blueberries costs $2.75.

• 2.75 pounds of blueberries cost $1.

• 5 pounds of blueberries cost $15.50.

• 12 pounds of blueberries cost $33.

• The point (3,9) is on the graph of the proportional relationship.