To determine which two points indicate a rate of change of 80 km per hour, we can use the formula for the rate of change between two points \((t_1, d_1)\) and \((t_2, d_2)\):
\[ \text{Rate of change} = \frac{d_2 - d_1}{t_2 - t_1} \]
We need the rate of change to be 80 km/h. Let's calculate the rate of change for each pair of points provided.
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Points (4, 480) and (6, 600): \[ \text{Rate} = \frac{600 - 480}{6 - 4} = \frac{120}{2} = 60 \text{ km/h} \]
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Points (5, 400) and (6, 560): \[ \text{Rate} = \frac{560 - 400}{6 - 5} = \frac{160}{1} = 160 \text{ km/h} \]
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Points (4, 320) and (6, 480): \[ \text{Rate} = \frac{480 - 320}{6 - 4} = \frac{160}{2} = 80 \text{ km/h} \]
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Points (4, 400) and (6, 480): \[ \text{Rate} = \frac{480 - 400}{6 - 4} = \frac{80}{2} = 40 \text{ km/h} \]
From these calculations, the only pair of points that gives a rate of change of 80 km per hour is:
(4, 320) and (6, 480).