Introduction / Context:
Seating-arrangement questions test your ability to translate compact verbal constraints into a precise linear order. Here we have six friends (A, B, C, D, E, F) seated in a single row facing North. We must use all given conditions to pin down the unique arrangement and then report who sits immediately to the left of D. Because everyone faces North, “left” and “right” are interpreted from the point of view of the people, which matches our usual left-to-right diagram on paper.
Given Data / Assumptions:
- Single row; all face North (so position index increases left to right).
- C is between A and E immediately (i.e., one of A/E – then C – then the other, consecutively).
- D is not at an end.
- B is immediately to the right of E (E, B are consecutive in that order).
- F is not at the right end.
- D is exactly third to the left of E (so D's position = E's position − 3).
Concept / Approach:
Convert the language into algebraic/positional relations. Use indexing 1..6 from left to right. Immediate-right/left constraints and fixed gaps (like “third to the left”) are especially powerful. Treat “C between A and E (immediately)” as a 3-block pattern A-C-E or E-C-A in consecutive positions. Combine with “E-B” consecutive order and “D = E − 3”. Eliminate placements that violate ends or contradictions.
Step-by-Step Solution:
1) Let positions be 1 2 3 4 5 6 (left → right). All face North, so this matches their left-to-right.2) From “D is third to the left of E”: position(D) = position(E) − 3. Therefore E cannot be at 1–3; valid E are {4,5,6} and D will be {1,2,3} respectively.3) “B is immediately to the right of E”: so (E, B) occupy consecutive positions (E at k, B at k+1). Hence E ≠ 6 (otherwise B would need position 7). So E ∈ {4,5} and then B ∈ {5,6}.4) “F is not at the right end”: so F ≠ 6. Keep this in mind for later pruning.5) “C is sitting between A and E (immediately)”: the only allowed consecutive triples are either A-C-E or E-C-A, in consecutive positions.6) Try E = 5 → then B = 6. With D = E − 3, D = 2. Since F is not at right end (6 is taken by B), F can be at {1,3,4}. Now place the triple A-C-E as consecutive. If we choose A-C-E occupying positions 3-4-5, that fits E = 5, so A = 3 and C = 4. Remaining person for position 1 is F. The full row becomes: (1) F, (2) D, (3) A, (4) C, (5) E, (6) B. All constraints check out: D not at end; E-B consecutive; F not at right end; D is exactly three left of E; and C indeed immediately between A and E.7) In this unique consistent arrangement, immediately to the left of D (which is at position 2) sits F (at position 1).
Verification / Alternative check:
Attempting E = 4 leads to conflicts with the required consecutive triple and the E-B block placement when all other constraints are enforced; the consistent completion found above satisfies every statement simultaneously. A quick re-scan confirms no rule is violated.
Why Other Options Are Wrong:
- A: In the valid arrangement A is two seats to the right of D, not immediately left.
- E: E is three seats to the right of D (by rule), not immediately left.
- C: C sits to the right of D (two places away), not immediately left.
- None of these: Incorrect because F is a valid listed option and is indeed immediately left of D.
Common Pitfalls:
- Misreading “between” as a non-consecutive positioning. Here it is immediate adjacency (A-C-E or E-C-A).
- Forgetting that everyone faces North; your left-to-right drawing already aligns with “left”/“right”.
- Overlooking the E-B consecutive order; this quickly restricts E's possible positions.
Final Answer:
F
Discussion & Comments