A Guide to the GRE/Percentages

Percentages
Percentage is a fraction of 100. 11% = .11 =

Percent simply means “per hundred.” However, be careful not to mix up the two key ways in which percentages are used.

Do not mix up changing to a percentage with changing by a percentage.

If a group of 100 members decreases to 20% of its membership, its membership goes down to 20. If the group decreases by 20%, it goes down to 80. Increasing to 110% is the same as increasing by 10%. This also applies to fractions and decimals but is an especially common error with percentages.

Practice
 {What is 30% of 80? { 24 }
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{(Questions 2-3) If a bank account worth $10,000 increased in value by 25%...}

{...how much did it increase? ${ 2,500|2500 }
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{...how much is it worth now? ${ 12,500|12500 }
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{(Questions 4-5) If a bank account worth $10,000 decreased in value to 25% of its worth...}

{...how much did it decrease? ${ 7,500|7500 }
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{...how much is it worth now? ${ 2,500|2500 }
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