All SAT Mathematics Resources
Example Questions
Example Question #441 : Sat Math
A rectangular label with an area of square inches. is wrapped around a can that is inches tall, such that the label exactly covers the outside of the can excluding the top and the bottom. What is the volume of the can, in cubic inches?
The surface area of a cylinder is calculated as a top, a bottom, and the outside. The outside is measured as the circumference * height, or . That will be the same size as the label. Therefore, . We know that , therefore, , and .
The volume of the cylinder is calculated as . Make sure that you square the full thing, . You will end up with .
Example Question #442 : Sat Math
if a cube has a volume of , what is its total surface area?
The volume of a cube is (that's why you call to the third power "-cubed"), where represents the length of one of the sides. The surface area is , or more conceptually the sum of the areas of each of the six faces (top, bottom, front, back, left, right) of the cube.
So if the volume of a cube is , that means that , so .
Plugging that into the surface area formula, you have which is .
Example Question #1 : Working With 3 D Shapes
A trophy shop has been commissioned to create spherical trophies for a soccer tournament. Each spherical soccer trophy has a radius of 1 inch, while an actual regulation soccer ball has a radius of 4 inches. Which of the following expresses the ratio of the volume of the spherical trophy to the volume of the actual soccer ball?
4:1
1:64
1:4
64:1
1:64
When looking to find the relationship between the volumes of the two spherical figures in the question stem, we’ll want to keep in mind the formula for the volume of a sphere:
So, if we plug each radius into this formula, we’ll arrive at:
Thus, the ratio between the two volumes is:
Since the component cancels in both the numerator and the denominator, the ratio of the volumes is 1:64. Be sure to arrange the ratio in the order asked for in the question stem! Additionally, you’ll want to keep in mind that when a change in scale is applied to multiple dimensions, the scale changes exponentially! We can actually save some time on questions like this if we recognize this relationship.
For instance, here, the “scale factor,” or change in scale from the smaller radius to the larger radius is 4, but since the relationship we’re looking for compares volume to volume, we need to account for the fact that the scale factor has been taken to the third power for the three dimensional measurement at hand. Thus, the ratio of the volumes will be 1 to 43, or 1 to 64.
Example Question #1 : Using Radians
Give in radians:
First we need to convert degrees to radians by multiplying by :
Now we can write:
Example Question #2 : Using Radians
Give in radians:
First, we need to convert to radians by multiplying by :
Now we can solve the following equation for :
Example Question #3 : Using Radians
How many degrees are in radians?
Since , we can solve by setting up a proportion:
Cross multiply and solve.
Example Question #4 : Using Radians
Change the following expression to degrees:
First, we need to simplify the expression:
Now multiply by :
Example Question #5 : Using Radians
Convert the following expression to radians:
First, we need to simplify the expression:
In order to change degrees to radians, we need to multiply by :
Example Question #6 : Using Radians
Simplify and give the following expression in degrees:
First, we need to simplify the expression:
Then multiply by :
Example Question #7 : Using Radians
Convert radians into degrees.
Recall the definition of "radians" derived from the unit circle:
The quantity of radians given in the problem is . All that is required to convert this measure into degrees is to denote the unknown angle measure in degrees by and set up a proportion equation using the aforementioned definition relating radians to degrees:
Cross-multiply the denominators in these fractions to obtain:
or
.
Canceling like terms in these equations yields
Hence, the correct angle measure of in degrees is .