To determine if the relationship between time walking (in minutes) and calories burned is proportional, we need to check if the ratio of calories burned to time walked is constant for all the data points.
Let's calculate the ratio of calories burned to minutes walked for each time interval:
- For 20 minutes: \( \frac{100 \text{ calories}}{20 \text{ minutes}} = 5 \)
- For 30 minutes: \( \frac{150 \text{ calories}}{30 \text{ minutes}} = 5 \)
- For 40 minutes: \( \frac{200 \text{ calories}}{40 \text{ minutes}} = 5 \)
- For 60 minutes: \( \frac{300 \text{ calories}}{60 \text{ minutes}} = 5 \)
- For 80 minutes: \( \frac{400 \text{ calories}}{80 \text{ minutes}} = 5 \)
Since the ratio of calories burned to minutes walked is constant (5) for all the data points, the relationship is indeed proportional.
Thus, the correct response is:
The relationship is proportional.