GCSE Maths (AQA)

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Percentage Decrease

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Ratio, Proportion and Rates of Change Ratio, Proportion and Rates of Change

Percentage Decrease

4:31 Percentage Change
Spec R9
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  • Decreasing a number by a percentage involves subtracting that percentage of the number
  • A percentage is a way of writing a proportion of a number as the number of parts out of 100
  • To work out the percentage of a value, convert the percentage to a fraction or decimal and then multiply
  • Example: decrease 150 by 12% (convert 12% to 0.12, multiply 150 by 0.12, subtract the result from 150 to get 132)
  • Another method is to subtract the percentage from 100% and apply it to the initial value
  • Example: decrease 150 by 40% (subtract 40% from 100% to get 60%, multiply 5 by 0.6 to get 3)
  • Example: decrease the price of a 550 television by 30% (subtract 30% from 100% to get 70%, multiply 550 by 7/10 to get 385)

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