fractions, decimal and percentage

• Percentages used in everyday life


  • This essay has been graded at 58%
  • 72% of women think that...
  • Interest rates have risen by 0.5%
  • Sale: Up to 70% off!
• Percent


  Means 'of 100', and any percentage can be written as a fraction of 100
• Percentages written as fractions

  • 25% = 25/100 = 1/4
  • 120% = 120/100 = 6/5
  • 0.75% = 0.75/100 = 75/10000 = 3/400
• Dealing with decimal points in percentages

  1. Multiply above and below by 100

  2. Cancel above and below
• If 55% of the pupils in a school are girls


  45% are boys
• If the Western Region contributes £15M profits to the Global Total of £370M

  The fraction would be 15/370 = 3/74
• Percentages written as decimals

  Also called proportions
• Percentages written as decimals

  • 75% = 0.75
  • 0.2% = 0.002
  • 115% = 1.15
• If ABC Ltd gets 28% of its revenue from telesales


  The proportion is 0.28
• Decimals expressed as fractions and percentages

  • 0.55 = 55/100 = 55%
  • 0.1 = 10/100 = 10%
  • 0.02 = 2/100 = 2%
  • 0.007 = 0.7/100 = 0.7%
  • 1.08 = 108/100 = 108%
  • 0.932 = 93.2/100 = 93.2%
• Calculating percentage from fractions

  Region A: 1/5

  Region B: 4/7

  Total from A and B: 1/5 + 4/7 = 0.7714 = 77.14%

  Percentage from Region C: 100% - 77.14% = 22.86%