a) To find the edge length from the volume you use the formula:
e = V¹ˡ³ (to the power of 1/3) where e is the edge length.
Substitute in the volume:
e = 64000¹ˡ³
Solve:
Edge length = 40 inches
b) To find the surface area from the volume you use the formula:
s = 6V²ˡ³ (to the power of 2/3) where s is the surface area.
Substitute in the volume:
s = 6 x 64000²ˡ³
Solve:
s = 384000²ˡ³
Surface area = 9600 square inches