Key words for ratio and proportion

Ratio is a way in which quantities can be divided or shared.

Example:
Share £20 between two people in a ratio of 3:1.
A ratio of 3 + 1 = 4 parts, the money needs to be divided into 4 parts.
      20 ÷ 4 = £5.
If one person is getting three parts they will have 3 x 5 = £15
The other person will have one part, £5.

Simplest form. Ratios can be simplfied by finding common factors.

Direct proportion. Ratios are in direct proportion when they increase or decrease in the same ratio.

Equivalent ratios. When both sides of a ratio can be multiplied or divided by the same number to give an equivalent ratio.

Example:
In a group there are 15 males and 12 females. What is the ratio of males to females? Give your example in its simplest form.
So the ratio of males to females is 15:12. However, both sides of the ratio can be divided by 3. Dividing 15 and 12 by 3 gives 5:4.
      5:4 is the ratio in its simplest form.
      5:4 and 15:12 are equivalent ratios.

Factor
The factors of a number are those numbers which divide into it exactly.

Example:
      1 x 12 = 12
      2 x 6 = 12
      3 x 4 = 12
So the factors of 12 are 1, 2, 3, 4, 6 and 12.

You'll find more maths words explained in the Skillswise Glossary.