- Percentage or per cent means hundredths. ∴ 34% is another way of writing 34/100
- The symbol ‘%’ is short for per cent.
- To change a percentage to a fraction, write it as a fraction of 100 and reduce it to its lowest terms, where possible.
- To change a fraction to a percentage, multiply the fraction by 100.
- To express a quantity as a percentage of another:
- make sure they are in the same units,
- express the first as a fraction of the second,
- multiply the fraction by 100.
Examples
- Express 15% as a fraction in its lowest terms.
- 15% = 15/100 = 3 × 5/20 × 5 = 3/20
- Express 2/5 as a percentage.
- 2/5 = 2 × 20/5 × 20
- = 40/100
- = 40%
- A worker hammers a post 2.2 m long into the ground. 66 cm of the post is below the ground. What percentage of the post is above the ground?
- Fraction of post below the ground = 66 cm/2.2 m = 66 cm/220 cm = 66/220
- Percentage of the post below the ground = 66/220 × 100% = 6/20 × 100 = 30%
- ∴ Percentage of post above the ground = 100% – 30% = 70%