Lesson 14: Practice Problems

Problem 1

The equation shows how much it costs to buy gas at a gas station on a certain day. In the equation, represents the cost in dollars, and represents how many gallons of gas were purchased.

  1. Write down at least four (gallons of gas, cost) pairs that fit this relationship.

  2. Create a graph of the relationship.

    blank grid

  3. What does 2.95 represent in this situation?

  4. Jada’s mom remarks, “You can get about a third of a gallon of gas for a dollar.” Is she correct? How did she come up with that?

Problem 2

There is a proportional relationship between a volume measured in cups and the same volume measured in tablespoons. 3 cups is equivalent to 48 tablespoons, as shown in the graph.

  1. Plot and label at least two more points that represent the relationship.

    A point plotted in the coordinate plane with the origin labeled “O”. The horizontal axis is labeled “volume in cups” and the numbers 0 through 6 are indicated. The vertical axis is labeled “volume in tablespoons” and the numbers 0 through 70, in increments of 10, are indicated. There are four evenly spaced horizontal gridlines between each number indicated. The point with coordinates 3 comma 48 is indicated.

  2. Use a straightedge to draw a line that represents this proportional relationship.

  3. For which value y is () on the line you just drew?

  4. What is the constant of proportionality for this relationship?

  5. Write an equation representing this relationship. Use for cups and for tablespoons.