Each of the six different faces of a cube has been coated with a different colour i.e., V, I, B, G, Y and O. Following information is given : 1. Colours Y, O and B are on adjacent faces. 2. Colours I, G and Y are on adjacent faces. 3. Colours B, G and Y are on adjacent faces. 4. Colours O, V and B are on adjacent faces. Which is the colour of the face opposite to the face coloured with O ?
- (a) B
- (b) V
- (c) G ✓ UPSC's answer
- (d) I
Why the answer is (c)
• Y is adjacent to O and B (1), to I and G (2), and to B and G (3). So Y's four neighbours are O, B, I and G, and Y must be opposite V.
• B is adjacent to Y and O (1), to G (3) and to V (4). So B's neighbours are Y, O, G and V, and B must be opposite I.
• The only faces left are O and G, so they are opposite each other.
• Hence the face opposite O is G, option (c).
Why the other options are wrong
- (a) B
- O and B are on adjacent faces (statement 1), so B cannot be opposite O.
- (b) V
- O and V are on adjacent faces (statement 4), so V cannot be opposite O.
- (d) I
- I is opposite B, not O.
Asked in the CSAT Paper II of the UPSC Civil Services Preliminary Examination 2015, held on 23 August 2015. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.