# GRE Math : How to find the surface area of a sphere

## Example Questions

### Example Question #1 : How To Find The Surface Area Of A Sphere

Find the surface area of a sphere with a diameter of 14. Use π = 22/7.

1256

2464

616

872

428

616

Explanation:

Surface Area = 4πr2 = 4 * 22/7 * 72 = 616

### Example Question #2 : How To Find The Surface Area Of A Sphere

A sphere has a surface area of square inches.  If the radius is doubled, what is the surface area of the larger sphere?

Cannot be determined

Explanation:

The surface area of the larger sphere is NOT merely doubled from the smaller sphere, so we cannot double to find the answer.

We can use the surface area formula to find the radius of the original sphere.

r2 = 4

r = 2

Therefore the larger sphere has a radius of 2 * 2 = 4.

The new surface area is then  square inches.

### Example Question #3 : How To Find The Surface Area Of A Sphere

If a sphere has a volume of  cubic inches, what is its surface area?

Explanation:

The volume of a cube is equal to .

So we mutiply our volume by  and divide by , giving us .

The surface area of a sphere is equal to , giving us .