Consider the following : A, B, C, D, E, F, G and H are standing in a row facing North. B is not neighbour of G. F is to the immediate right of G and neighbour of E. G is not at the extreme end. A is sixth to the left of E. H is sixth to the right of C. Which one of the following is correct in respect of the above?
- (a) C is to the immediate left of A.
- (b) D is immediate neighbour of B and F.
- (c) G is to the immediate right of D. ✓ UPSC's answer
- (d) A and E are at the extreme ends.
Why the answer is (c)
• Number the positions 1 to 8 from the left. "A is sixth to the left of E" gives (A, E) = (1, 7) or (2, 8); "H is sixth to the right of C" gives (C, H) = (1, 7) or (2, 8).
• These pairs cannot share positions, so one is (1, 7) and the other (2, 8). If E were at 8, F (E's neighbour, just right of G) would have to be at 7, which is H's position — impossible. So A = 1, E = 7, C = 2, H = 8.
• F is next to E and just right of G, so F = 6 and G = 5 (not at an end).
• B is not next to G, so B cannot be at 4; B = 3 and D = 4.
• Order: A, C, B, D, G, F, E, H. G is immediately right of D, option (c).
Why the other options are wrong
- (a) C is to the immediate left of A.
- C is at position 2 and A is at position 1, so C is to the immediate right of A, not the left.
- (b) D is immediate neighbour of B and F.
- D is at position 4; its neighbours are B (pos 3) and G (pos 5), so D is not a neighbour of F (pos 6).
- (d) A and E are at the extreme ends.
- A is at position 1 (extreme left) but E is at position 7, which is not an extreme end (H is at 8).
Asked in the CSAT Paper II of the UPSC Civil Services Preliminary Examination 2017, held on 18 June 2017. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.