Question 5·Medium·Area and Volume
A right circular cylinder has a radius of meters and a volume of cubic meters.
What is the height, in meters, of the cylinder?
(Express the answer as an integer)
For volume questions with standard 3D shapes, first recall and write down the correct formula (here, for a cylinder). Then plug in the given values and solve for the unknown variable, canceling common factors like early to simplify the arithmetic. On the SAT, be careful with exponents such as and check your final step when dividing to isolate the variable to avoid small arithmetic mistakes.
Hints
Recall the relevant formula
For a right circular cylinder, the volume involves , the radius squared, and the height. Think about how these three pieces fit together in one formula.
Substitute known values
Once you have the formula, plug in and . You should get an equation with only one unknown, .
Isolate the height
After substituting, simplify and then look for common factors on both sides (especially involving ) to make solving for easier.
Desmos Guide
Compute the height from the formula
In Desmos, type the expression 108*pi/(pi*3^2) to represent . The numerical value that Desmos outputs is the height of the cylinder in meters.
Step-by-step Explanation
Write the formula for the volume of a cylinder
The volume of a right circular cylinder with radius and height is given by
We are given and and need to solve for .
Substitute the given values into the formula
The problem states that the radius is meters and the volume is cubic meters.
Substitute and into the formula:
Compute :
Simplify and solve for the height
First, notice that appears on both sides of the equation, so you can divide both sides by to cancel it:
Now solve for by dividing both sides by :
So, the height of the cylinder is 12 meters.