GRE Math : GRE Quantitative Reasoning

Study concepts, example questions & explanations for GRE Math

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Example Questions

Example Question #55 : Percentage

Sally buys a dress that is a 20% discount from the original price. If she sells it at a 10% markup from her purchase price and profits $10 from the sale, what was the original price of the dress?

Possible Answers:

20

110

125

100

120

Correct answer:

125

Explanation:

Set Original = O

and Discount = D

then 

D = (1 – 20%) x O = 0.80 x O

and Profit = $10 so:

10 = ((1 + 10%) x D) – D = 1.1 * D – D = 0.1D

D = 100

and O = D / 0.8 = 125

Example Question #56 : Percentage

A shirt costs $12 to manufacture. If the marketing and sales costs are a 75% addition to this manufacturing cost. What is the minimum price necessary for making a 50% profit?

Possible Answers:

$31.5

$16.5

$10.5

$21

$18

Correct answer:

$31.5

Explanation:

Based on the prompt, we know that the additional marketing and sales costs are 12 * 0.75 = 9; therefore, the total cost for purchase and sale is 12 + 9 = $21. To make a 50% profit, we must make 21 * 0.5, or $10.5, on the sale; thus the shirt must be sold for 21 + 10.5, or $31.5.

Example Question #57 : Percentage

A factory has fixed costs of $25,000 per month. It manufactures widgets at a total manufacturing cost of $45 per widget. They are sold at $60. How many widgets must be sold in any given month in order to break even?

Possible Answers:

1666

1667

555

556

1753

Correct answer:

1667

Explanation:

Let's first represent the total costs per month:

C = 25000 + 45n, where n is the number of widgets manufactured.

The profit can be represented as 60n – C or 60n – 25000 – 45n = 15n – 25000. Now, we merely have to solve this for 0 in order to find the "break even" line. 

15n – 25000 = 0 → 15n = 25000 → n = 1666.67.  We must sell a whole number of widgets, so it must be 1667.

Example Question #58 : Percentage

A boy with a lemonade stand sells cups of lemonade for a quarter each. He has bought  worth of supplies and is able to make  of lemonade with the supplies. If he has to pay a business tax of  for each cup he sells, how many cups will he have to sell in order to break even?

Possible Answers:

Correct answer:

Explanation:

To solve this problem we must first find out how cups he must sell without tax to break even. If each cup of lemonade costs a quarter and he has spent $20 on supplies, that means in order to make back the original $20 he spent, he must sell .  Due to this 4% business tax, he must sell 4% more in order to break even. To find that amount, we simply multiply that 4% by the number of cups he must sell without tax to break even, . He must sell an additional 3.2 cups in order to break even, however it is impossible to sell 0.2 of a cup of lemonade, therefore he must sell a minimum of 84 cups of lemonade in order to break even.

Example Question #1 : How To Find The Percent Of Increase

Harry and Gerry each own equal shares in a gardening company. Their partner, Izzy, owns 40% of the company. What is the percentage increase of the sum of Harry's and Gerry's shares above Izzy's share in the company?

Possible Answers:

33.3%

100%

20%

150%

50%

Correct answer:

50%

Explanation:

This basic percentage problem asks you to determine by what percentage the sum of Harry's and Gerry's share of the company is greater than ("exceeds") Izzy's share. Harry's and Gerry's share's are equal, and the sum is 60% of the company (100% – Izzy's 40% = 60%). 60% is 50% greater than 40% (0.40 * 1.5 = 0.60). Examinees may be tempted to go too far with the problem and mistake their task by finding how much greater Izzy's share is than either Harry's or Gerry's. Be careful to read instructions and translate keywords appropriately.

You may think the answer is 20% (60% – 40%), but this is the difference in terms of total shares in the company, not in terms of Izzy's shares, which is what the question is asking.

Example Question #1 : Percent Of Change

What is the percent change in the area of a circle if its circumference increases from 20 to 45?

Possible Answers:
406.25%
506.25%
225%
None of the other answers
125%
Correct answer: 406.25%
Explanation:

The circumference of a circle increases linearly with its radius.  Therefore, an increase in circumference from 20 to 45 represents an increase of (45 – 20) / 20 = 25 / 20 = 125% increase.  This means that if the radius was r, it is now r + 1.25r = 2.25r.

Now, the original area, supposing r as our radius, would be πr2

The new area would be π(2.25r)2 = 5.0625πr2

The percent change would be: (5.0625πr2 - πr2) / πr2  = (4.0625πr2) / πr2 = 4.0625 or 406.25%

Example Question #61 : Percentage

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According to the graph above, what was the percent change in the sales of camcorders from 2002-2006?

Possible Answers:

25%

17%

29%

40%

36%

Correct answer:

29%

Explanation:

For this problem, pay attention only to the values between 2002 and 2006 - each of which is 17 (thousand) and 22 (thousand). Note that the decrease within this range does not need to be accounted for, as the question asks only for values relative to 2002 and 2006. 

To calculate percent change, take it as a fraction: 22/17 = 1.294; this represents approximately 129% of the actual value or a 29% increase in sales across these 4 years.

Example Question #1 : How To Find The Percent Of Increase

What number is 150% greater than 6?

Possible Answers:

3

9

90

18

15

Correct answer:

15

Explanation:

In the problem, 150% of 6 represents the change in the value, not the new value. Percent "greater than" is a key phrase that refers to percent change. Therefore, 9, or 150% of 6, is how much 6 increases. The answer is 6 + 9 = 15.

Formula: Original * (1 + percent increase/100) = New

6(1 + 1.50) = 15

Example Question #62 : Percentage

Alex had an investment worth $1500. If the total investment increased 25% the first year and decreased 10% the next year, what is the final worth of the investment.

Possible Answers:

Correct answer:

Explanation:

Example Question #2 : Percent Of Change

Book sales increased by 50% from April 1st to 30th and then decreased by 50% from May 1st to May 31st. Determine the greater quanity.

Possible Answers:

The relationship cannot be determined

Book sales on April 1st

Book sales on May 31st

The quantities are equal

Correct answer:

Book sales on April 1st

Explanation:

If book sales were 100/day then an increase by 50% means they would reach 150/day (by the end of April). A decrease at that point means a 50% decrease in 150/day which would lower book sales to 75/day. Thus sales were higher at the beginning of April than at the end of May.

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