Question

Which graphs show functions with direct variation? Select three options.

A coordinate plane showing Parking Garage Rates with Time in hours on the x-axis and Total Cost in dollars on the y-axis with a line passing through points at (1, 2.4) and (5, 4).
A coordinate plane showing Cost of Cinnamons with Quantity in ounces on the x-axis and Total Cost in dollars on the y-axis with a line passing through points at (1, 0.3) and (5, 1.5).
A coordinate plane showing Breakfast Cost with Number of Meals on the x-axis and Total Cost in dollars on the y-axis with a line passing through points at (1, 1.2) and (5, 6).
A coordinate plane showing Ferry Ride Cost with Number of Persons on the x-axis and Total Cost in dollars on the y-axis with a line passing through points at (1, 2) and (5, 8).
A coordinate plane showing Ferry Ride Cost with Number of Persons on the x-axis and Total Cost in dollars on the y-axis with a line passing through points at (1, 2) and (5, 8).

Answer 1

The Cost of Cinnamons and the Breakfast Cost graphs.

Reason: For direct variation y = kx the ratio y/x must be constant (and the line goes through the origin).
- Cinnamons: 0.3/1 = 1.5/5 = 0.3 → yes.
- Breakfast: 1.2/1 = 6/5 = 1.2 → yes.

None of the other graphs have y/x constant, so there are only two direct-variation graphs (not three).