Numbers – Ratio

Ratio – how much of one thing there is compared to another 

. e.g if you have 5 squares, 3 red and 2 blue, the ratio of red squares to blue squares is 3:2

Example:

Out of 500 people, 320 have a flu.

Q1) How many people should be expected to have the flu out of 1250 people?

1. Workout the proportionality between 500 and 1250 people
2. Apply the same proportionality to the numerator.

A) 800

The ratio of girls to boys in a school is 4:3. There are 700 pupils in the school.

Q2) How many girls and boys are there in the school?

1. Add both ratios together – 4 + 3 = 7 → this tells us 47 of the pupils are girls and 37 are boys
2. 7 x 100 = 700 → 4 x 100 = 400 and 3 x 100 = 300. The x100 tell us the proportionality between the ratio and the real number of boys and girls

A) 400 girls and 300 boys