A solid cube is painted yellow, blue and black such that opposite faces are of same colour. The cube is then cut into 36 cubes of two different sizes such that 32 cubes are small and the other four cubes are Big. None of the faces of the bigger cubes is painted blue. How many cubes have only one face painted?
Size of bigger cubes is twice the size of smaller cubes. Also, as none of the faces of the bigger cubes is painted blue, so each one of the bigger cube has one face painted yellow, one is black and all other faces are unpainted.
Number of cubes with one face painted = 8
Number of cubes with two faces painted = 8 smaller cubes on each of blue painted surface + 4 bigger cubes
= (8 x 2) + 4 = 20
The correct option is C.