Question

The radius of a sphere is 4 inches. If the radius is doubled, how does that change the surface area of the sphere?aThe surface area is multiplied by fourbThe surface area is squaredcThe surface area is doubleddThe surface area is multiplied by eight

Answer 1

Solution:

Given the radius of the sphere is 4inches.

The surface area, A, of the sphere is;

$\begin{gathered} A=4\pi r^2 \\ \\ A=4\pi(4^2) \\ \\ A=201.06in^2 \end{gathered}$

But when the radius is doubled;

$\begin{gathered} r=8in \\ \\ A=4\pi(8^2) \\ \\ A=804.25in^2 \end{gathered}$

Hence, when the radius is doubled, the surface area is multiplied by four.