The graph below shows how the amount of water in a bathtub is changing over time.

Which equation describes the relationship between x, the time in minutes, and y, the amount of water in gallons?

1 answer

To determine the equation that describes the relationship between time \( x \) (in minutes) and the amount of water \( y \) (in gallons) in a bathtub, we typically need to analyze the characteristics of the graph.

  1. Identify Key Points: Look for two distinct points on the graph. For example, if \( (0, 0) \) indicates that at time 0 minutes there are 0 gallons of water, and if at \( (5, 10) \) there's 10 gallons at 5 minutes.

  2. Determine the Slope: The slope \( m \) can be calculated using the formula: \[ m = \frac{\Delta y}{\Delta x} = \frac{y_2 - y_1}{x_2 - x_1} \] For the points mentioned: \[ m = \frac{10 - 0}{5 - 0} = \frac{10}{5} = 2 \]

  3. Form the Equation: With the slope calculated, the linear equation can be written in the slope-intercept form \( y = mx + b \). If the y-intercept \( b \) is 0 (since it starts at 0 when time is 0), the equation simplifies to: \[ y = 2x \]

Using these steps would allow you to determine the correct linear equation. If you can provide specific points or characteristics from the graph, then I could give you a more precise equation.