Final answer:
The top speed for heavy trucks on rural interstates at night varies by state, but typical highway speeds can range from 80 km/h to 100 km/h, equivalent to 50 mph to 62 mph.
Step-by-step explanation:
The top speed for heavy trucks on designated rural interstates at nighttime is not universally fixed and can vary by state and local regulations. However, to find a specific value, we need to reference the provided information from practice problems specifically related to speed limits and convert if necessary. When converting speeds from kilometers per hour to miles per hour, we can use the conversion factor where 1.0 mile is about 1.609 km. For example, a speed limit of 100 km/h is approximately equivalent to 62 miles per hour.
Since the speed limits given in the exercises range from 80 km/h to 100 km/h, we can infer these are typical speed limits for vehicles on highways, which might include trucks. However, heavy trucks may have lower speed limits for safety reasons. It's recommended to check the specific state highway departments for accurate speed limit information for heavy trucks at night.