What is a Ratio?
A ratio is a comparison in terms of a quotient of two numbers a and b, usually written as $ \frac{a}{b} $ or a/b.
Science regularly requires us to compare values. Ratios are used to compare the amount of one number to another number.
Ratios can be expressed as;
1 to 5 1 : 5 $ \frac15 $ or 1 / 5
No matter which notation is used for this ratio, it is read as "1 to 5".
You will have probably encountered ratios in your everyday life. Some potential examples include;
- The ratio of girls to boys in a class is 4 : 3
- A pancake recipe requires a flour to milk ratio of 3 : 2
- A model aeroplane has a scale of 1 : 48
Ratios should be expressed in their simplest form. For example, a ratio of 25 to 5 can be simplified to;
$ \frac{25}{5} = \frac51 $ or 25/5 = 5/1. For example, a laboratory solution contains 58.5 grams of NaCl per litre. Expressed as a ratio, this would be 58.5g / 1 L