Percentage change as a fraction or decimal

Sample Percentage change as a fraction or decimal questions

A few of the 48 questions, from easier to harder. Choose your exam board and tier to practise them, with every answer marked.

1. Question 12 marksGrade 2
   Ed buys a particular card for £1.20 and sells it for £1.68. Calculate his percentage profit on this card.
   Show the worked solution

   Profit = £1.68 − £1.20 = £0.48. M1

   Percentage profit = 0.48/1.20 × 100 = 40%. A1
2. Question 22 marksGrade 5-6
   A population is going to increase by 18%. Write down the single decimal multiplier that represents this change.
   Show the worked solution

   A increase of 18% means the new amount is 100% + 18% of the original. M1

   Convert this to a decimal: $100 + 18 = 118\% = 1.18$

What are the common mistakes in Percentage change as a fraction or decimal?

When a pupil makes one of these on Revision Workshop, the marking engine names the mistake and explains it, instead of just marking the answer wrong.

• Gives an intermediate value (e.g. before the final division/simplification) as the final answer

  Gave only the multiplier for the first change (0.9), forgetting to combine it with the second change's multiplier

• Uses repeated addition (a constant difference) to scale a ratio/proportion instead of multiplying by a scale factor

  Added the two percentage changes together (-10% + -15%) and used that as the single change, instead of multiplying the two separate multipliers - successive percentage changes compound, they don't add

• Applies the wrong inverse operation when isolating the unknown (e.g. subtracts instead of adding, or vice versa)

  Wrote the multiplier for the opposite direction of change (a decrease instead of an increase)

Quick answers about Percentage change as a fraction or decimal

How many Percentage change as a fraction or decimal practice questions are there?

There are 48 self-marking GCSE and IGCSE Maths questions on Percentage change as a fraction or decimal, written for AQA, Pearson, OCR, Pearson International GCSE Maths A (4MA1), Cambridge IGCSE Mathematics (0580), Cambridge IGCSE (9-1) Mathematics (0980) across Foundation and Higher and Core and Extended tier. Each one is marked instantly and has a full worked solution.

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