Percentages (Edexcel GCSE Maths: Foundation): Flashcards
Exam code: 1MA1
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True or False?
If a number has been increased by 20%, to find the original number you decrease the new number by 20%.
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Cards in this collection (5)
True or False?
If a number has been increased by 20%, to find the original number you decrease the new number by 20%.
False.
If a number has been increased by 20%, you can not find the original number by decreasing the new number by 20%.
You would divide by 1.2.
If you are given the new number after a percentage increase or decrease, how do you find the original number?
E.g. Find the original amount given that it was increased by 15% to 80.5.
Find the multiplier for the percentage change, e.g. 15% increase = 1.15.
Divide the new number by the multiplier, e.g. 80.5 ÷ 1.15 = 70.
What is the multiplier when a number has been decreased by 45%?
The multiplier for a 45% decrease is 0.55.
Subtract 45 from 100 and then divide by 100.
True or False?
A number has been decreased by 10%.
To find the original number, multiply the new number by 0.9.
False.
A number has been decreased by 10%.
To find the original number, divide the new number by 0.9.
Do not multiply.True or False?
A number has been increased by 80%.
To find the original number, divide the new number by 0.8.
False.
A number has been increased by 80%.
To find the original number, divide the new number by 1.8, not 0.8.
You need to add 80 to 100 and then divide by 100 to find the multiplier.
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