if the diameter of a spherical ball is doubled,by what factor does its surface area increase?

Answer 1

Isn't surface area proportional to the square of diameter?

Answer 2

yes but don't know wat surface area it increases

Answer 3

SA of sphere is 2pi(r)^2

so if you change the radius from r to 2r (or d to 2d)
then the SA is 2pi(2r)^2 = 8pir^2

so by what factor did it increase ?