Edexcel IGCSE Maths 复习笔记 1.11.1 Ratios

Edexcel IGCSE Maths 复习笔记 1.11.1 Ratios

What is a ratio?

  • ratio is a way of comparing one part of a whole to another
  • ratio can also be expressed as a fraction (of the whole)
  • We often use a ratio (instead of a fraction) when we are trying to show how things are shared out or in any situation where we might use scale factors

 How to work with ratios

  1. Put what you know in RATIO form (use more than one line if necessary)
  2. Add “extra bits” (eg Total, Difference, Sum) if you think they might be useful
  3. Use SCALE FACTORS to complete lines
  4. Pick out the ANSWER!

Exam Tip

One less obvious place to use Ratios is when dealing with Currency Conversion problems – see Exchange Rates.

Worked Example