# Expressing One Quality as a Fraction of Another

## Quantities as fractions of another

- Often when we compare things we want to compare quantities as fractions of something.
- Fractions compare things against wholes.

Let’s go through some examples:

**Example 1**

You have a class, where there are 23 girls and 17 boys in total we have 40 students.

This means the whole class = 40 students

Therefore if we want to express the fraction of girls in the class, we would put 23/40, the fraction of boys in the class would be 17/40. Both of these fractions are out of 40 because 40 is the number of students in total, **the whole**.

**Example 2**

The whole here is £80, which means £80 will be our denominator, and we have £5 of that £80, so £5 will be our numerator.

Therefore we can write this as **1/16** here I have simplified the fraction by dividing the top and bottom by 5.

- 1. Kate buys some drinks, she buys 4 coffees , 3 cans of coke and 1 frappe. What fraction of drinks does she have that are coffees?
- Your answer should include: 4/8 / 1/2
- In an exam hall Mr Peterson collects mobile phones from the students. There are 23 iphones, 17 Samsung’s and 10 other makes. What fraction of the phones are other makes?
- Your answer should include: 10/50 / 1/5
- In a biscuit tin 6 biscuits are custard creams, 8 are bourbons and 3 are jammy dodgers. What fraction are jammy dodgers?
- 3/17