You have a map of an area in France. The scale used is 2cm:8km you want to ride to a national park. The park is shown on the map as 16 cm away. How far is that in kilometres?

Question

You have a map of an area in France. The scale used is 2cm:8km. You want to ride to a national park. The park is shown on the map as 16cm away. How far is that in kilometres?

Answer 1

The scale (2cm:8km) can be written as a ratio two different ways: 2cm/8km or 8km/2cm. The distance you have is the distance on the map (in cm), and you want to convert it to the distance in the park (in km). You need to write the ratio so that when you multiply it by the distance, the units cancel and you're left with the distance in the park, so set it up as 16cm × 8km/2cm. In your answer, you can start by multiplying and dividing the numbers: 16 × 8/2=64. The units in the answer are cm × km/cm. The 'cm' in the numerator and denominator cancel, and you're left with 'km', so the final answer is 64 km.