All GRE Math Resources
Example Questions
Example Question #301 : Geometry
Quantity A:
The -intercept of the line
Quantity B:
The -intercept of the line
The relationship cannot be determined from the information given.
Quantity B is greater
Quantity A is greater
The two quantities are equal.
The two quantities are equal.
The key to these quantitative comparison problems is to figure out the worth of both quantities, or figure out whether evaluating the quantities is even possible. In this case, evaluating the quantities is a fairly straightforward case of figuring out the intercepts of two different lines, which is possible. Therefore, you can already discount "the relationship cannot be determined from the information given".
To solve quantity A: is in form, where is the -intercept. Therefore, the -intercept is equal to .
To solve quantity B: , you have to sole for the intercept. The quickest way to figure out the answer is to remember that the axis exists at the line , therefore to find out where the line crosses the axis, you can set and solve for .
-3.5 = .5x - 1.5
Both quantity A and quantity B , therefore the two quantities are equal.
Example Question #1 : X And Y Intercept
What is the -intercept of the following equation?
To find the -intercept, you must plug in for .
This leaves you with
.
Then you must get you by itself so you add to both sides
.
Then divide both sides by to get
.
For the coordinate point, goes first then and the answer is .
Example Question #1 : How To Find The Equation Of A Curve
What is the slope of the line whose equation is ?
Solve for so that the equation resembles the form. This equation becomes . In this form, the is the slope, which is .
Example Question #2 : X And Y Intercept
Which of the following equations has a -intercept of ?
To find the -intercept, you need to find the value of the equation where . The easiest way to do this is to substitute in for your value of and see where you get for . If you do this for each of your equations proposed as potential answers, you find that is the answer.
Substitute in for :
Example Question #3 : X And Y Intercept
If is a line that has a -intercept of and an -intercept of , which of the following is the equation of a line that is perpendicular to ?
If has a -intercept of , then it must pass through the point .
If its -intercept is , then it must through the point .
The slope of this line is .
Therefore, any line perpendicular to this line must have a slope equal to the negative reciprocal, which is . Only has a slope of .
Example Question #1 : Solid Geometry
The area of the base of a circular right cylinder is quadrupled. By what percentage is the outer face increased by this change?
100%
300%
200%
250%
400%
100%
The base of the original cylinder would have been πr2, and the outer face would have been 2πrh, where h is the height of the cylinder.
Let's represent the original area with A, the original radius with r, and the new radius with R: therefore, we know πR2 = 4A, or πR2 = 4πr2. Solving for R, we get R = 2r; therefore, the new outer face of the cylinder will have an area of 2πRh or 2π2rh or 4πrh, which is double the original face area; thus the percentage of increase is 100%. (Don't be tricked into thinking it is 200%. That is not the percentage of increase.)
Example Question #305 : Geometry
What is the surface area of a cylinder with a radius of 17 and a height of 3?
3107
1984
2000
2137
2205
2137
We need the formula for the surface area of a cylinder: SA = 2πr2 + 2πrh. This formula has π in it, but the answer choices don't. This means we must approximate π. None of the answers are too close to each other so we could really even use 3 here, but it is safest to use 3.14 as an approximate value of π.
Then SA = 2 * 3.14 * 172 + 2 * 3.14 * 17 * 3 ≈ 2137
Example Question #1501 : Gre Quantitative Reasoning
What is the surface area of a cylinder with a radius of 6 and a height of 9?
96π
64π
180π
108π
225π
180π
surface area of a cylinder
= 2πr2 + 2πrh
= 2π * 62 + 2π * 6 *9
= 180π
Example Question #306 : Geometry
Quantitative Comparison
Quantity A: The volume of a cylinder with a radius of 3 and a height of 4
Quantity B: 3 times the volume of a cone with a radius of 3 and a height of 4
The two quantities are equal.
Quantity A is greater.
The relationship cannot be determined from the information given.
Quantity B is greater.
The two quantities are equal.
There is no need to do the actual computations here to find the two volumes. The volume of a cone is exactly 1/3 the volume of a cylinder with the same height and radius. That means the two quantities are equal. The formulas show this relationship as well: volume of a cone = πr2h/3 and volume of a cylinder = πr2h.
Example Question #2 : Solid Geometry
A right circular cylinder of volume has a height of 8.
Quantity A: 10
Quantity B: The circumference of the base
The two quantities are equal
The relationship cannot be determined from the information provided.
Quantity A is greater
Quantity B is greater
Quantity B is greater
The volume of any solid figure is . In this case, the volume of the cylinder is and its height is , which means that the area of its base must be . Working backwards, you can figure out that the radius of a circle of area is . The circumference of a circle with a radius of is , which is greater than .