GRE Math : How to find percentage
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Example Questions
Example Question #851 : Gre Quantitative Reasoning
Quantity A:
Quantity B:
Quantity A is greater.
The two quantities are equal.
The relationship cannot be determined.
Quantity B is greater.
Quantity B is greater.
To attempt this problem, translate the statements into mathematical equations. When you see the word 'is', it very often means 'equals:
Now before we continue, look at this statement. We see that s is fourth fifths of r. That alone should tell us that r is greater! However, we can continue with the calculations to see what these values are, if only for the sake of robustness. However, on the GRE, once you find the answer like this, fill it in and move on.
Again, this validates our result. We may not know what r and s are, but we know how they relate to each other, and that is enough.
Quantity B is greater.
Example Question #852 : Gre Quantitative Reasoning
To solve this problem, translate 
Example Question #853 : Gre Quantitative Reasoning
In Dopolopolis, the first $20,000 dollars of a person's income is taxed at 6%, and any additional income they make is taxed at 10%. If Donny of Dopolopolis paid $2,000 in income tax this year, how much did Donny make?
All of the answer choices are above $20,000, so assume that Donny paid the 6% on that:
That means of the $2,000 he paid in taxes
$800 was taken from any income he made above the $20,000 line, and was thus taxed at 10%:
Donny's income must therefore have been
Example Question #854 : Gre Quantitative Reasoning
Forty percent of the 20 professors in a university's physics department are male. If two male professors and two female professors retire, what percentage of the department will be male after the change?
Begin by finding out how many of the 20 professors are male:
That means that there are eight males and twelve females currently to sum up to twenty.
Now, two males and two females leave, meaning the faculty is reduced by four:
The amount of males has been reduced by two:
Therefore, the percentage of the faculty that is male can be found as the number of males divided by the total faculty size times 100:
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