# High School Math : How to find the volume of a cylinder

## Example Questions

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### Example Question #21 : How To Find The Volume Of A Cylinder

What is the surface area of a cylinder with a base diameter of  and a height of ?

Explanation:

Area of a circle

Circumference of a circle

Surface area of a cylinder

### Example Question #21 : How To Find The Volume Of A Cylinder

A balloon, in the shape of a sphere, is filled completely with water.  The surface area of the filled balloon is .   If all of the balloon's water was emptied into a cylindrical cup of base radius 4, how high would the water level be?

Explanation:

The surface area of a sphere is given by the formula

, which here equals  .   So

To find out what the water level would be, we need to know how much water is in the balloon.  So we need to find the volume of the balloon.

The amount of water that is in the balloon is

=

The cylindrical column of water will have this volume, and will have base radius 4. Using the formula for volume of a cylinder, we can solve for the height of the column of water.

, where  is the base radius 4 in this case.

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