1. **State the problem:** We are given a graph showing the outflow of water (in litres) from a tank over time (in hours). We need to find the gradient of the line, interpret it, and determine if the outflow rate is constant or variable. 2. **Find the gradient of the line:** The gradient (slope) of a line is given by the formula: $$\text{gradient} = \frac{\text{change in } y}{\text{change in } x} = \frac{\Delta y}{\Delta x}$$ From the graph, the line passes through the origin $(0,0)$ and the point $(12,4000)$. So, $$\text{gradient} = \frac{4000 - 0}{12 - 0} = \frac{4000}{12}$$ 3. **Simplify the gradient:** $$\frac{4000}{12} = \frac{\cancel{4000}}{\cancel{12}} = \frac{1000}{3} \approx 333.33$$ 4. **Interpret the gradient:** The gradient represents the rate of change of outflow with respect to time. Here, it means the tank is losing water at a rate of approximately 333.33 litres per hour. 5. **Determine if the rate is constant or variable:** Since the graph is a straight line, the gradient is constant throughout the time period. This means the rate of outflow is constant. **Final answers:** - Gradient: $\frac{1000}{3} \approx 333.33$ litres per hour - Interpretation: The tank loses water at a constant rate of about 333.33 litres every hour. - Rate: Constant, as evidenced by the straight line on the graph.