How are scales and ratios related?

Question

7385 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2018-05-30T11:29:19

A scale is always in the form $1 : n$

A ratio compares two or more quantities.

A scale is a specific type of ratio.

It compares a unit on a map or plan or on a scaled model to an actual distance on a map or the size of a real object.

A scale is given in the form: $" "1" ":" "n$

On a map, a scale of $" "1:50" "$ means

$" "1cm$ on the map represents $50cm$ on the ground (in reality)

or $" "200mm" "$ on a plan to this scale, indicates a length of
$200xx50=10,000mm$ in reality.

A ratio is a comparison between two or more quantities of the same type.

e.g: girls : boys are in the ratio $4:3$ means that:

for every $4$ girls there are $3$ boys.

If there are $35$ children in a class with this ratio, we have:

$4/7$ of the class are girls (which means $4/7 xx35 = 20$ girls.)

$3/4$ of the class are boys (which means $3/7xx35 = 15$ boys.)