Answer:
The ratio that represents the scale of the map, showing how the map measurements compare to actual ones on Earth's surface, is 1 cm to 2 km.
Step-by-step explanation:
The scale of a map represents the relationship between the measurements on the map and the actual measurements on the Earth's surface. In this case, the given information states that every 3 cm on the map represents 6 km on the Earth's surface.
To express this as a ratio, you can compare the map measurements to the actual measurements:
Map Measurement : Actual Measurement
3 cm : 6 km
However, it's common to simplify ratios by dividing both sides by a common factor. In this case, you can divide both sides by 3 to simplify the ratio:
1 cm : 2 km
So, the ratio that represents the scale of the map, showing how the map measurements compare to actual ones on Earth's surface, is 1 cm to 2 km.