What is a ratio?
A ratio compares two amounts. If there are 2 red apples and 3 green apples, we write the ratio of red to green as 2 : 3. We read it as "2 to 3". The order matters: red first, then green.
Key idea
To make a ratio simpler, divide both numbers by the same number, until you cannot divide any more.
Simplifying a ratio
A simpler ratio is easier to understand, just like a simpler fraction. We look for a number that divides both sides exactly.
Worked example
A class has 4 boys and 6 girls. The ratio of boys to girls is 4 : 6. Both numbers can be divided by 2: 4 ÷ 2 = 2 and 6 ÷ 2 = 3. So 4 : 6 = 2 : 3. This means for every 2 boys there are 3 girls.
Remember
- Keep the order the same when you write a ratio.
- Divide both sides by the same number to simplify.
- 1 : 1 means the two amounts are equal.