a sphere has a surface area of 900pie feet squared. find the volume of the sphere

We need to solve for the radius. So using the "formula" for the surface area, we have

900*pi ft^2 = 4*pi*r^2       divide by pi

900 ft^2 = 4*r^2    divide by 4

225ft^2 = r^2         take the square root of each side

15 ft = r

Now, the "formula" for the volume is

V_s = (4/3)*pi*r^3

V_s = (4/3)*pi*(15ft)^3 = about 14,137 cu ft.