All GRE Math Resources
Example Questions
Example Question #2 : How To Find The Diagonal Of A Cube
You have a rectangular box with dimensions 6 inches by 6 inches by 8 inches. What is the length of the shortest distance between two non-adjacent corners of the box?
The shortest length between any two non-adjacent corners will be the diagonal of the smallest face of the rectangular box. The smallest face of the rectangular box is a six-inch by six-inch square. The diagonal of a six-inch square is .
Example Question #1 : How To Find The Diagonal Of A Cube
What is the length of the diagonal of a cube with side lengths of each?
The diagonal length of a cube is found by a form of the distance formula that is akin to the Pythagorean Theorem, though with an additional dimension added to it. It is:
, or , or
Now, if the the value of is , we get simply
Example Question #3 : How To Find The Diagonal Of A Cube
What is the length of the diagonal of a cube that has a surface area of ?
To begin, the best thing to do is to find the length of a side of the cube. This is done using the formula for the surface area of a cube. Recall that a cube is made up of squares. Therefore, its surface area is:
, where is the length of a side.
Therefore, for our data, we have:
Solving for , we get:
This means that
Now, the diagonal length of a cube is found by a form of the distance formula that is akin to the Pythagorean Theorem, though with an additional dimension added to it. It is:
, or , or
Now, if the the value of is , we get simply
Example Question #1 : How To Find The Volume Of A Cube
What is the volume of a rectangular box that is twice as long as it is high, and four times as wide as it is long?
4L3
8
2L2
5L
2L3
2L3
The box is 2 times as long as it is high, so H = L/2. It is also 4 times as wide as it is long, so W = 4L. Now we need volume = L * W * H = L * 4L * L/2 = 2L3.
Example Question #1 : How To Find The Volume Of A Cube
What is the volume of a cube with a surface area of ?
The surface area of a cube is merely the sum of the surface areas of the squares that make up its faces. Therefore, the surface area equation understandably is:
, where is the side length of any one side of the cube. For our values, we know:
Solving for , we get:
or
Now, the volume of a cube is defined by the simple equation:
For , this is:
Example Question #24 : Solid Geometry
The volume of a cube is . If the side length of this cube is tripled, what is the new volume?
Recall that the volume of a cube is defined by the equation:
, where is the side length of the cube.
Therefore, if we know that , we can solve:
This means that .
Now, if we triple to , the new volume of our cube will be:
Example Question #2 : How To Find The Volume Of A Cube
What is the volume of a cube with surface area of ?
Recall that the equation for the surface area of a cube is merely derived from the fact that the cube's faces are made up of squares. It is therefore:
For our values, this is:
Solving for , we get:
, so
Now, the volume of a cube is merely:
Therefore, for , this value is:
Example Question #3 : How To Find The Volume Of A Cube
A cube has a volume of 64, what would it be if you doubled its side lengths?
To find the volume of a cube, you multiple your side length 3 times (s*s*s).
To find the side length from the volume, you find the cube root which gives you 4
.
Doubling the side gives you 8
.
The volume of the new cube would then be 512
.
Example Question #1 : How To Find The Surface Area Of A Cube
A rectangular box is 6 feet wide, 3 feet long, and 2 feet high. What is the surface area of this box?
72 sq ft
36 sq ft
64 sq ft
48 sq ft
22 sq ft
72 sq ft
The surface area formula we need to solve this is 2ab + 2bc + 2ac. So if we let a = 6, b = 3, and c = 2, then surface area:
= 2(6)(3) + 2(3)(2) +2(6)(2)
= 72 sq ft.
Example Question #2 : How To Find The Surface Area Of A Cube
What is the surface area of a rectangular box that is 3 feet high, 6 feet long, and 4 feet wide?
108
72
84
144
96
108
Surface area of a rectangular solid
= 2lw + 2lh + 2wh
= 2(6)(4) + 2(6)(3) + 2(4)(3)
= 108