Asphere has radius 7 cm. if the radius is multiplied by 4, what is the effect on the surface area?

surface area of a sphere= 4pi*r^2

S.A when radius is 7 is:

=4pi*(7)^2

=196pi cm^2

if you multiply radius by 4, the equation becomes:

4pi*(4r)^2

=4pi*16r^2

=64pi*r^2

substitute 7 into equation:

=64pi*(7)^2

=64pi*49

=3136pi cm^2

Divide new S.A. by old S.A. to show effect:

=3136pi/196pi

=16

If the radius is multiplied by 4, the effect on the surface area is that it is 16 times the surface area of the sphere where the radius is not multiplied.

step-by-step explanation: