ACT Math : How to find the diameter of a sphere
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Example Questions
Example Question #3 : Spheres
If a sphere has a volume of 
1. Use the volume to find the radius:
2. Use the radius to find the diameter:
Example Question #1 : How To Find The Diameter Of A Sphere
A sphere has a volume of 
Cannot be determined from the information given
This question relies on knowledge of the formula for volume of a sphere, which is as follows: 
In this equation, we have two variables, 
Rearranged form:
Plug in 
Simplify the part under the cubed root
1) Cancel the 
2) Simplify the fraction and the 
Thus we are left with
Then, either use your calculator and enter 
We're almost there, but we need to go a step further. Dodge the trap answer "
So
Example Question #1 : Spheres
A spherical plastic ball has a diameter of 
To answer this question, we must calculate the volume of the ball using the equation for the volume of a sphere. The equation for the volume of a sphere is four-thirds multiplied by pi, which is then multiplied by the radius cubed. The equation can be written like this:
We are given the diameter of the sphere in the problem, which is 
We can then plug our newly found radius of two into the equation to find the volume. For this data:
We then multiply 
We finally substitute 3.14 for pi and multiply again to get our answer.
The question asked us to round to the nearest whole cubic inch. To do this, we round a number up one place if the last digit is a 5, 6, 7, 8, or 9, and we round it down if the last digit is a 1, 2, 3, or 4. Therefore:
Therefore our answer is 
Example Question #1 : Spheres
A boulder breaks free on a slope and rolls downhill. It rolls for 
The formula for the volume of a sphere is:
To figure out how far the sphere rolled, we need to know the circumference, so we must first figure out radius. Solve the formula for volume in terms of radius:
Since the answer asks us to round to the nearest integer, we are safe to round 
To find circumference, we now apply our circumference formula:
If our boulder rolled 
Thus, our boulder rolled for
Example Question #1 : How To Find The Diameter Of A Sphere
Find the diameter of a sphere whose radius is 
To solve, simply remember that diameter is twice the radius. Don't be fooled when the radius is an algebraic expression and incorporates the arbitrary constant 
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