When a spherical balloon filled with air diameter of 6 inches what's the volume of balloon in cubic inches

Volume of sphere: V (s) = 4/3*pi*R^3 = (4/3) * pi * (D/2) ^3 = (1/6) * pi * D^3

Volume of cube: V (c) = s^3

Volume of them is the same, I'm assuming you actually want to know the length of the cubic vertice

So s^3 = (1/6) * pi*D^3 - > s = (1/6 * pi) ^1/3 * 6 = (36pi) ^1/3