Q1. A cube is coloured red on all faces. It is cut into 125 smaller cubes of equal size. How many cubes are coloured on one face only?
A 36
B 48
C 54 Correct
D 60
Explanation
Since 125 smaller cubes are formed, the large cube is cut as 5 by 5 by 5. Cubes with colour on exactly one face lie in the inner part of each face, excluding edges and corners. On one face, that count is (5 - 2) x (5 - 2) = 3 x 3 = 9. There are 6 faces, so the total is 6 x 9 = 54. The counts 36, 48 and 60 do not follow this face-centre formula and include too few or too many small cubes.