Final answer:
The temperature is changing by -4 degrees Fahrenheit per hour on average during the snowstorm.
Step-by-step explanation:
To find the average rate at which the temperature is changing per hour, we need to determine the change in temperature per hour. In this case, the temperature drops from 0 degrees Fahrenheit to -12 degrees Fahrenheit in 3 hours. The change in temperature is -12°F - 0°F = -12°F.
Dividing the change in temperature by the number of hours gives us the average rate of change: -12°F / 3 hours = -4°F per hour.
Therefore, on average, the temperature is changing by -4 degrees Fahrenheit per hour during the snowstorm.