Question

A sphere has diameter 28 cm. If the diameter is divided by 2, what is the effect on the surface area?

The surface area is divided by 8.
The surface area is multiplied by 8.
The surface area is multiplied by 4.
The surface area is divided by 4.

Answer 1

The surface area is divided by 4.

Explanation:

Surface area of a sphere is 4πr².

When the diameter is 28 the radius is 14. So: 4π(14)² = 784π

If you cut the diameter in half you get 14. The radius is now 7.

4π(7)² = 196π.

784/4 = 196 so divided by 4.