Edexcel IGCSE Maths復習筆記 1.7.2 Percentage Increases & Decreases

Edexcel IGCSE Maths復習筆記 1.7.2 Percentage Increases & Decreases

How do I increase or decrease by a percentage?

• Identify “before” & “after” quantities
• Find percentage of “before” that we want:
  • Increase – add percentage to 100
  • Decrease – subtract percentage from 100

   

• Write down a statement connecting “before” and “after”:
  • “after is a percentage of before”

   

• Write down the statement as an equation using decimal equivalent
  • remember “is” means “=”

   

• Substitute and solve

How do I find percentage profit (or loss)?

• Calculate percentage profit (or loss)

• You can identify whether there is a profit or loss
  • cost price < selling price = profit (positive)
  • cost price > selling price = loss (negative)

Worked Example

轉載自savemyexam