Final answer:
The rate of change between hour 2 and hour 7 is 21 miles per hour.
Step-by-step explanation:
To determine the rate of change between hour 2 and hour 7, we need to calculate the average speed of the family's travel.
First, we calculate the distance traveled during this time period by subtracting the distance at 2 hours (375 mi) from the distance at 7 hours (480 mi), which gives us 105 mi.
Next, we calculate the time elapsed by subtracting 2 hours from 7 hours, which gives us 5 hours.
Finally, we divide the distance traveled by the time elapsed to find the average speed, which is 105 mi / 5 hr = 21 miles per hour.