Every cube has 6 sides and assuming that each face is numbered 1 to 6, the faces that he has to get when he rolls the cubes for the sum to be 10 should be 4 and 6, 5 and 5 or 6 and 4. The probability for each cube is therefore 1/3 and since the combination is Cube1 AND Cube2 you multiply the probabilities (if it were OR, you'd have to add instead)
so the total probability is [tex] \frac{1}{3} * \frac{1}{3} = \frac{1}{9} [/tex]
