Comparing Fractions & Percentages (SQA National 5 Applications of Mathematics): Revision Note

Exam code: X844 75

Dan Finlay

Written by: Dan Finlay

Reviewed by: Roger B

Updated on

Comparing fractions & percentages

How do I compare a fraction and a percentage?

  • You need to write both as either percentages or fractions

Convert the fraction to a percentage

  • You can easily compare a fraction and a percentage if they are both written as a percentage

    • With a calculator:

      • multiply the fraction by 100

    • Without a calculator:

      • divide 100% by the denominator

      • then multiply by the numerator

  • This method is quicker using a calculator

  • It can be tricky without a calculator if 100% doesn't divide nicely by the denominator

Convert the percentage to a fraction with the same denominator

  • You need to write the percentage as a fraction using the same denominator as the other fraction

  • Find the percentage of the denominator of the fraction

    • Consider 13 over 90 and 14%

      • 14 percent sign space of space 90 equals 0.14 cross times 90 equals 12.6 space

  • This then becomes the numerator

    • 14 percent sign equals fraction numerator 12.6 over denominator 90 end fraction

  • You can then just compare the numerators

    • 13 greater than 12.6

    • Therefore, 13 over 90 greater than 14 percent sign

Worked Example

Greg had two tests at school.

Greg scored 28 out of 40 in his Physics test.

Greg scored 72% in his Chemistry test.

Determine which subject Greg performed better in.

Answer:

Method 1

Write the Physics score as a fraction

28 over 40 equals 7 over 10

Divide 100% by the denominator and then multiply by the numerator

table row cell 100 percent sign divided by 10 end cell equals cell 10 percent sign end cell row cell 7 cross times 10 percent sign end cell equals cell 70 percent sign end cell end table

Compare the percentages

Greg performed better at Chemistry since 72% > 70%

Method 2

Write 72% as a decimal

72 divided by 100 equals 0.72

Find 72% of 40 and write 72% as a fraction out of 40

table row cell 0.72 cross times 40 end cell equals cell 28.8 end cell end table

72 percent sign equals fraction numerator 28.8 over denominator 40 end fraction

Compare the numerators

Greg performed better at Chemistry since 28.8 > 28

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Dan Finlay

Author: Dan Finlay

Expertise: Maths Subject Lead

Dan graduated from the University of Oxford with a First class degree in mathematics. As well as teaching maths for over 8 years, Dan has marked a range of exams for Edexcel, tutored students and taught A Level Accounting. Dan has a keen interest in statistics and probability and their real-life applications.

Roger B

Reviewer: Roger B

Expertise: Maths Content Creator

Roger's teaching experience stretches all the way back to 1992, and in that time he has taught students at all levels between Year 7 and university undergraduate. Having conducted and published postgraduate research into the mathematical theory behind quantum computing, he is more than confident in dealing with mathematics at any level the exam boards might throw at you.