A scale drawing shows a real object smaller or larger, with all lengths in the same ratio. A map scale of 1 cm to 5 km means every centimeter on the map is 5 kilometers in real life.
To find a real distance, multiply the map distance by the scale. 7 cm on the map is 7 × 5 = 35 km. A model car at a scale of 1 : 20 is 20 times smaller than the real car. To go from real to drawing, divide by the scale.
Worked example
A model is built to a scale of 1 : 50. The model is 18 cm long. How long is the real object?
- The real object is 50 times longer.
- 18 × 50 = 900 cm.
Answer:900 cm (9 m)
Key words
- scale
- the ratio between a drawing and real life
- scale factor
- how many times bigger or smaller
- model
- a smaller copy of a real object
Practise this
New questions every time.
Common Core-referenced: 7.G.A.1