Hello,

the surface of a cube exists of 6 squares. At least 25% of the surface must be painted that means that there are at least 2 squares of the surface painted in red.

You find 12 * 3 cubes with 2 painted squares along the edges (12) of the origianl cube

and 8 cubes with 3 painted squares at the vertices of the original cube.

Total 44 of 125 cubes have at least 25 % of their surface painted. Thus the probability is:

EB