All HSPT Math Resources
Example Questions
Example Question #2 : How To Find Surface Area
If the volume of a cube is 216 cubic units, then what is its surface area in square units?
108
36
216
54
64
216
The volume of a cube is given by the formula V = , where V is the volume, and s is the length of each side. We can set V to 216 and then solve for s.
In order to find s, we can find the cube root of both sides of the equaton. Finding the cube root of a number is the same as raising that number to the one-third power.
This means the length of the side of the cube is 6. We can use this information to find the surface area of the cube, which is equal to . The formula for surface area comes from the fact that each face of the cube has an area of , and there are 6 faces in a cube.
surface area =
The surface area of the square is 216 square units.
The answer is 216.
Example Question #3 : How To Find Surface Area
You have a cube with sides of 4.5 inches. What is the surface area of the cube?
The area of one side of the cube is:
A cube has 6 sides, so the total surface area of the cube is
Example Question #4 : How To Find The Surface Area Of A Cube
A cube has a surface area of 24. If we double the height of the cube, what is the volume of the new rectangular box?
We have a cube with a surface area of 24, which means each side has an area of 4. Therefore, the length of each side is 2. If we double the height, the volume becomes .
Example Question #4 : How To Find Surface Area
A cube has a surface area of 10m2. If a cube's sides all double in length, what is the new surface area?
320m2
20m2
80m2
640m2
40m2
40m2
The equation for surface area of the original cube is 6s2. If the sides all double in length the new equation is 6(2s)2 or 6 * 4s2. This makes the new surface area 4x that of the old. 4x10 = 40m2
Example Question #1 : How To Find The Surface Area Of A Prism
A rectangular prism has a volume of 70 m3. If the length, width, and height of the prism are integers measured in meters, which of the following is NOT a possible measure of the surface area of the prism measured in square meters?
174
214
280
118
178
280
Since the volume is the product of length, width, and height, and each of these three dimensions are integers, it is important to know the factors of the volume. 70 = (2)(5)(7). This implies that each of these factors (and only these factors with the exception of 1) will show up in the three dimensions exactly once. This creates precisely the following five possibilities:
2, 5, 7
SA = 2((2)(5)+(2)(7)+(5)(7)) = 118
1, 7, 10
SA = 2((1)(7)+(1)(10)+(7)(10)) = 174
1, 5, 14
SA = 2((1)(5)+(1)(14)+(5)(14)) = 178
1, 2, 35
SA = 2((1)(2)+(1)(35)+(2)(35)) = 214
1, 1, 70
SA = 2((1)(1)+(1)(70)+(1)(70)) = 282
Example Question #2 : How To Find The Surface Area Of A Prism
The three sides of a rectangular box all have integer unit lengths. If each of the side lengths is greater than one unit, and if the volume of the box is 182 cubic units, what is the surface area of the box in square units?
264
181
182
236
262
262
Let's call the side lengths of the box l, w, and h. We are told that l, w, and h must all be integer lengths greater than one. We are also told that the volume of the box is 182 cubic units.
Since the volume of a rectangular box is the product of its side lengths, this means that lwh must equal 182.
(l)(w)(h) = 182.
In order to determine possible values of l, w, and h, it would help us to figure out the factors of 182. We want to express 182 as a product of three integers each greater than 1.
Let's factor 182. Because 182 is even, it is divisible by 2.
182 = 2(91).
91 is equal to the product of 7 and 13.
Thus, 182 = 2(7)(13).
This means that the lengths of the box must be 2, 7, and 13 units.
In order to find the surface area, we can use the following formula:
surface area = 2lw + 2lh + 2hw.
surface area = 2(2)(7) + 2(2)(13) + 2(7)(13)
= 28 + 52 + 182
= 262 square units.
The answer is 262.
Example Question #1 : How To Find The Surface Area Of A Prism
A right rectangular prism has dimensions of 3 x 5 x 20. What is its surface area?
300
350
56
112
175
350
There are six faces to a right, rectangular prism. Based on our dimensions, we know that we must have a face that is 3 x 5, a face that is 5 x 20 and a face that is 3 x 20. To think this through, imagine that the front face is 3 x 5, the right side is 5 x 20, and the top is 3 x 20. Now, each of these sides has a matching side opposite (the left has the right, the top has the bottom, the front has the back).
Therefore, we know we have the following areas for the faces of our prism:
2 * 3 * 5 = 30
2 * 5 * 20 = 200
2 * 3 * 20 = 120
Add these to get the total surface area:
30 + 200 + 120 = 350
Example Question #12 : Prisms
A right rectangular prism has dimensions of 12.4 x 2.3 x 33. What is its surface area?
513.62
470.58
941.16
1027.24
1882.32
1027.24
There are six faces to a right, rectangular prism. Based on our dimensions, we know that we must have a face that is 12.4 x 2.3, a face that is 2.3 x 33 and a face that is 33 x 12.4. To think this through, imagine that the front face is 12.4 x 2.3, the left side is 2.3 x 33, and the top is 33 x 12.4. Now, each of these sides has a matching side opposite (the left has the right, the top has the bottom, the front has the back).
Therefore, we know we have the following areas for the faces of our prism:
2 * 12.4 * 2.3 = 57.04
2 * 2.3 * 33 = 151.8
2 * 12.4 * 33 = 818.4
Add these to get the total surface area:
57.04 + 151.8 + 818.4 = 1027.24
Example Question #71 : Solid Geometry
The dimensions of a right rectangular prism are such that the second dimension is twice the length of the first and the third is twice the length of the second. If the volume of the prism is 216 cubic units, what is its surface area?
252 square units
126 square units
215 square units
189 square units
None of the other answers
252 square units
Based on our prompt, we can say that the prism has dimensions that can be represented as:
Dim1: x
Dim2: 2 * Dim1 = 2x
Dim3: 2 * Dim2 = 2 * 2x = 4x
More directly stated, therefore, our dimensions are: x, 2x, and 4x. Therefore, the volume is x * 2x * 4x = 216, which simplifies to 8x3 = 216 or x3 = 27. Solving for x, we find x = 3. Therefore, our dimensions are:
x = 3
2x = 6
4x = 12
Or: 3 x 6 x 12
Now, to find the surface area, we must consider that this means that our prism has sides of the following dimensions: 3 x 6, 6 x 12, and 3 x 12. Since each side has a "matching" side opposite it, we know that we have the following values for the areas of the faces:
2 * 3 * 6 = 36
2 * 6 * 12 = 144
2 * 3 * 12 = 72
The total surface area therefore equals: 36 + 144 + 72 = 252 square units.
Example Question #3 : How To Find The Surface Area Of A Prism
The area of a given object is 30,096 in2. What is the area of this object in ft2?
None of the other answers
209 ft2
2508 ft2
1254 ft2
1881 ft2
209 ft2
Converting squared units is not difficult, though you have to be careful not to make a simple mistake. It is tempting to think you can merely divide the initial value (30,096) by 12, as though you were converting from inches to feet.
Begin by thinking this through as follows. In the case of a single dimension, we know that:
1 ft = 12 in or 1 in = (1/12) ft
Now, think the case of a square with dimensions 1 ft x 1 ft. This square has the following dimensions in inches: 12 in x 12 in. The area is therefore 12 * 12 = 144 in2. This holds for all two-dimensional conversions. Therefore, the two dimensional conversion equation is:
1 ft2 = 144 in2 or 1 in2 = (1/144) ft2
Based on this, we can convert our value 30,096 in2 thus: 30,096/144 = 209 ft2.