A scale is written as a representative fraction (RF) by expressing the relationship between a distance on a map (or model) and the corresponding distance on the ground as a ratio. While it can be shown as a fraction, like 1/24,000, it is more commonly written using a colon, such as 1:24,000.
This format means that one unit of measurement on the map (e.g., 1 cm, 1 inch) represents 24,000 of the same units on the ground. The representative fraction is dimensionless, meaning that the units used on both sides of the ratio must be the same. This allows it to be used with any unit of measurement desired.
For example:
- 1:100,000 indicates that 1 cm on the map represents 100,000 cm (or 1 km) on the ground.
- 1:63,360 indicates that 1 inch on the map represents 63,360 inches (or 1 mile) on the ground.
In summary, to write a scale as a representative fraction, express the map distance to ground distance as a ratio using a colon, ensuring both sides of the ratio are in the same units. This provides a scale that can be easily applied, regardless of the unit of measurement chosen.
