Finding the original quantity after a percentage increase
Sometimes you have a final amount after a percentage increase or decrease. You can use this to find the original amount.
A bottle of lemonade advertises that it’s now 50% bigger. If it is now 750 ml, what was its original volume?
Answer
- Start with the original volume as 100%
- The new volume is 50% more than this: 100% + 50% = 150%
- 150% = 750 ml. We can divide by 150 to find 1%.
- 1% = 5 ml. We can now multiply by 100 to find 100%, which was the original volume.
- 100% = 500 ml
