GRE Math : How to find the percent of increase

Study concepts, example questions & explanations for GRE Math

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Example Questions

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Example Question #11 : Percent Of Change

A city originally had a  sales tax, but increased it to .  Assuming that the rate of consumption in the city does not change, what was the total amount of sales tax collected when the rate was if the increase in tax brought in an additional  in revenue?

Possible Answers:

Correct answer:

Explanation:

One way to solve this is by considering that the increase in taxes is a linear addition of 2%.  Therefore we can ask the question, 2% of what amount yields $150,000?  This can be represented in the following equation:

0.02 * x = 150,000

Solve for x: $7,500,000

Therefore, the total at the old rate is 7,500,000 * 0.06 = $450,000.

Example Question #291 : Arithmetic

In 2014, approximately  of Americans were considered charming. In 2013 approximately 27.1% of Americans were deemed charming. If the population of America in 2013 was  people and the population of America in 2014 was roughly  people, what is the percent increase/decrease of charming people from 2013-2014? Round to the nearest tenth.

Possible Answers:

Correct answer:

Explanation:

To solve this problem, we must understand that we can't simply use the percentage change from 2013-2014 in order to solve this problem. Because the populations change, simply using the percentage change in order to is invalid. Therefore we must find the amount of people that were charming in each year to solve for this problem.

In 2013,  of the  people in America were considered charming, this means that the number of charming people in America in 2013 is   people.

 

In 2014,  of the  people in America were considered charming, this means that the number of charming people in America in 2014 is   people.

 

Therefore to find the percent increase of charming people, we simply find the difference in charming people from 2013-2014 and divide by the number of charming people in 2013.   or a  increase in charming people. 

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