There's a formula for the surface area of a sphere:
A = 4*pi*r^2
Here, A = 4*pi*(15/2 yd)^2 = 706.9 sq yd, or approx 707 sq yd
Use the same formula to determine the radius of the sphere of surface area 482.8 mm^3. Then use the formula V = (4/3)*pi*r^3 to find the volume of this sphere.