The scale in a scale drawing is often shown as a ratio.
A ratio of 1:100 means that 1 cm on the drawing represents 100 cm in actual real life.
This could also be written as 1 cm:1 m or 1 cm to 1 m.
This means that a scale of 1 cm to 5 m could also be written as 1:500.
Betty makes a scale drawing of her classroom.
She uses a scale of 1 cm to 2 m.
The actual length of her classroom is 10 m.
How long should she make her classroom, in cm, on her drawing?
The ratio is 1 cm to 2 m.
Every 2 m in real life is shown as 1 cm on the drawing.
10 m is 5 × 2 m.
On the drawing, this should be 5 cm.
Charlie makes a scale drawing of the school hall.
The actual length of the hall is 25 m.
On his drawing, he makes the hall 5 cm long.
What scale is Charlie using?
The ratio is 5 cm to 25 m.
This reduces like a fraction by dividing both numbers by 5.
So the ratio is 1 cm to 5 m.
This is 1 cm to 500 cm or 1:500.