Translate each condition
- Immediately right: the next position, with no gap.
- Somewhere right: a later position, possibly with people between.
- At an end: the first or last position.
- Not adjacent: leave at least one position between the people.
Decide whether left and right refer to the page or to a seated person’s perspective. In the worked row below everyone faces north, so a person’s right is to the right on the page. South-facing or mixed-facing arrangements need a separate direction check.
Worked row: four people
A, B, C and D sit in a row facing north. B is immediately to the right of A. C is at the left end. D is not at the right end. Who occupies the right end?
- Number the seats 1 to 4 from left to right. Put C in seat 1.
- Treat A–B as a block because they must be adjacent in that order.
- Test the block in seats 2–3 and 3–4.
- Reject any placement that forces D into seat 4.
“Must” and “could” ask different questions
A “could be true” option needs at least one valid arrangement. A “must be true” option must hold in every valid arrangement. Finding one layout is not sufficient to prove a must statement unless the layout is unique.
If an item adds a condition, apply it only to that item. Do not carry a temporary condition into the next question in a shared set.
Try a slightly larger row
Five people P, Q, R, S and T face north in a row. R is in the middle. P is immediately left of Q. T sits at the right end. What is the full order?
Reveal the layout and explanation
R occupies seat 3 and T seat 5. The P–Q block cannot use seats 2–3 or 3–4 because R is there, and it cannot use 4–5 because T is there. It must occupy 1–2. S fills seat 4. The order is P, Q, R, S, T.
When the arrangement is circular
Fix one person’s position to remove rotations before placing the others. Draw a facing arrow and work out left or right from that person’s viewpoint. Do not count a rotated version of the same relative seating as a new arrangement unless the problem gives named seats or fixed locations.
Check before choosing
Read each rule against your diagram. Then answer the exact question: person, position, neighbour or possible order. If two valid arrangements produce different answers to a must question, keep searching or check for missing information.
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