Edexcel IGCSE Maths复习笔记 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)