Relating Ratios and Fractions

## Relating Ratios and Fractions

Ratios can be written as a fraction: fractions may also be written as a ratio.

A ratio compares sizes of quantities that make up a total. A fraction compares a quantity against a total.

To turn a ratio into a fraction,add the two parts of the ratio together to make a total: this will become the denominator. A ratio of 3 : 5 can be turned into two fractions of frac(3)(8) and frac(5)(8).

## Example 1

Write frac(3)(16) as a ratio.

The first part of the ratio uses the numerator, 3.

Work out the second numerator as denominator - numerator.

16 - 3 gives the second part of the ratio as 13.

The answer is 3 : 13.

This is a fraction of frac(3)(12) which simplifies to frac(1)(4).
Answer: frac(1)(4)