GRE Math : GRE Quantitative Reasoning

Study concepts, example questions & explanations for GRE Math

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Example Questions

Example Question #1 : How To Find The Length Of The Side Of A Parallelogram

Parallelogram gre

Using the parallelogram shown above, find the length of side 

Possible Answers:

Correct answer:

Explanation:

A parallelogram must have two sets of congruent/parallel opposite sides. Therefore, this parallelogram must have two sides with a measurement of  and two base sides each with a length of  Since the perimeter and one base length is provided in the question, work backwards using the perimeter formula:

, where  and  are the measurements of adjacent sides. 

Thus, the solution is:







Example Question #1342 : Gre Quantitative Reasoning

A parallelogram has a base of . The perimeter of the parallelogram is . Find the sum of the two adjacent sides to the base. 

Possible Answers:

Correct answer:

Explanation:

A parallelogram must have two sets of congruent/parallel opposite sides. This parallelogram must have two sides with a measurement of  and two base sides each with a length of . In this question, you are provided with the information that the parallelogram has a base of  and a total perimeter of . Thus, work backwards using the perimeter formula in order to find the sum of the two adjacent sides to the base.

, where  and  are the measurements of adjacent sides. 

Thus, the solution is:





Example Question #1343 : Gre Quantitative Reasoning

A parallelogram has a base of . An adjacent side to the base has a length of . Find the perimeter of the parallelogram. 

Possible Answers:

Correct answer:

Explanation:

A parallelogram must have two sets of congruent/parallel opposite sides. Therefore, this parallelogram must have two sides with a measurement of  and two base sides each with a length of  To find the perimeter of the parallelogram apply the formula: 

, where  and  are the measurements of adjacent sides. 

Thus, the solution is:





Example Question #25 : Quadrilaterals

A parallelogram has a base of . The perimeter of the parallelogram is . Find the length for an adjacent side to the base. 

Possible Answers:

Correct answer:

Explanation:

A parallelogram must have two sets of congruent/parallel opposite sides. Therefore, this parallelogram must have two sides with a measurement of  and two base sides each with a length of . To solve for the missing side, work backwards using the perimeter formula: 

, where  and  are the measurements of adjacent sides. 

Thus, the solution is:







Example Question #1341 : Gre Quantitative Reasoning

A quadrilateral has equal sides, each with a length of .

Quantity A: The area of the quadrilateral.

Quantity B: The perimeter of the quadrilateral.

Possible Answers:

The relationship cannot be determined.

The two quantities are equal.

Quantity A is greater.

Quantity B is greater.

Correct answer:

The relationship cannot be determined.

Explanation:

We are told that the shape is a quadrilateral and that the sides are equal; beyond that, we do not know what specific kind of kind of quadrilateral it is, outside of the fact that it is a rhombus. The perimeter, the sum of the sides, is .

If this shape were a square, the area would also be ; however, if the interior angles were not all equivalent, the area would be smaller than this.

The relationship cannot be determined.

Example Question #151 : Plane Geometry

A rectangle has an area of 48 and a perimeter of 28.  What are its dimensions?

Possible Answers:

2 x 24

0.25 x 192

1 x 48

6 x 8

16 x 3

Correct answer:

6 x 8

Explanation:

We can set up our data into the following two equations:

(Area) LH = 48

(Perimeter) 2L + 2H = 28

Solve the area equation for one of the two variables (here, length): L = 48 / H

Place that value for L into ever place you find L in the perimeter equation: 2(48 / H) + 2H = 28; then simplify:

96/H + 2H = 28

Multiply through by H: 96 + 2H2 = 28H

Get everything on the same side of the equals sign: 2H2 - 28H + 96 = 0

Divide out the common 2: H2 - 14H + 48 = 0

Factor: (H - 6) (H - 8) = 0

Either of these multiples can be 0, therefore, consider each one separately:

H - 6 = 0; H = 6

H - 8 = 0; H = 8

Because this is a rectangle, these two dimensions are the height and width.  If you choose 6 for the "height" the other perpendicular dimension would be 8 and vice-versa.  Therefore, the dimensions are 6 x 8.

Example Question #31 : Quadrilaterals

The length of a rectangle is three times its width, and the perimeter is . What is the width of the rectangle?

Possible Answers:

Correct answer:

Explanation:

For any rectangle, \dpi{100} \small P=2L+2W, where \dpi{100} \small P=perimeter, \dpi{100} \small L=length, and \dpi{100} \small W=width

In this problem, we are given that \dpi{100} \small L=3W (length is three times the width), so replace \dpi{100} \small L in the perimeter equation with \dpi{100} \small 3W: \dpi{100} \small P=2(3W)+2W

Plug in our value for the perimeter, \dpi{100} \small P:

\dpi{100} \small 16=2(3W)+2W

Simplify:

\dpi{100} \small 16=6W+2W 

\dpi{100} \small 16=8W

\dpi{100} \small W=2

Example Question #1 : Rectangles

The area of a rectangle is . Its perimeter is . What is the length of its shorter side?

Possible Answers:

Correct answer:

Explanation:

We know that the following two equations hold for rectangles. For area:

For perimeter:

Now, for our data, we know:

Now, solve the first equation for one of the variables:

Now, substitute this value into the second equation:

Solve for :

Multiply both sides by :

Solve as a quadratic. Divide through by :

Now, get the equation into standard form:

Factor this:

This means that  (or ) would equal either  or . Therefore, your answer is .

 

Example Question #1 : How To Find The Length Of The Diagonal Of A Rectangle

Given Rectangle ABCD.

Quantity A: The length of diagonal AC times the length of diagonal BD

Quantity B: The square of half of ABCD's perimeter

Possible Answers:

Quantity A is greater. 

The relationship cannot be determined from the information given. 

The two quantities are equal. 

Quantity B is greater. 

Correct answer:

Quantity B is greater. 

Explanation:

 

Suppose ABCD has sides a and b. 

The length of one of ABCD's diagonals is given by a2+ b2 = c2, where c is one of the diagonals.

Note that both diagonals are of the same length. 

Quantity A: The length of diagonal AC times the length of diagonal BD

This is c * c = c2.

Quantity A = c2 = a2+ b2 

 

Now for Quantity B, remember that the perimeter of a rectangle with sides a and b is Perimeter = 2(a + b).

Half of Perimeter = (a + b)

Square Half of Perimeter = (a + b)2 

Use FOIL: (a + b)2 = a2+ 2ab + b2 

Quantity B = (a + b)2 = a2+ 2ab + b2 

 

The question is asking us to compare a2+ b2 with a2+ 2ab + b2.

Note that as long as a and b are positive numbers (in this case a and b are dimensions of a rectangle, so they must be positive), the second quantity will be greater. 

 

 

 

 

Example Question #152 : Geometry

If rectangle  has a perimeter of , and the longer edge is  times longer than the shorter edge, then how long is the diagonal ?

Possible Answers:

Correct answer:

Explanation:

Lets call our longer side L and our shorter side W.

If the perimeter is equal to 68, then

.

We also have that

.

If we then plug this into our equation for perimeter, we get .

Therefore,  and . Using the Pythagorean Theorem, we have  so .

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