Six boys are so standing that they form a circle, each facing the centre. Rabi…
2023
Six boys are so standing that they form a circle, each facing the centre. Rabi is to the left of Ramen, Subrata is between Abir and Biman, Bimal is between Rabi and Abir. Who is to the left of Bimal?
Answer: C. Abir — Concept. When people stand in a circle and every one of them faces the centre, "left" is a single fixed rotational sense that is the same for all of them:…
- A.
Rabi
- B.
Subrata
- C.
Abir
- D.
Ramen
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Show answer & explanation
Correct answer: C
Concept. When people stand in a circle and every one of them faces the centre, "left" is a single fixed rotational sense that is the same for all of them: whichever way round the ring one person's left hand points, every other person's left hand points the same way round. A clue of the form "P is to the left of Q" therefore carries two pieces of information at once — P and Q are neighbours, and P is the very next person after Q when you walk around the ring in that left-sense. Chaining enough such neighbour clues fixes the entire cyclic order, after which "who is to the left of X" is answered simply by reading one step onward from X in the same sense.
Application. Take the "left" sense as the direction of travel and build the ring one clue at a time.
"Rabi is to the left of Ramen" makes the two of them neighbours and puts Rabi immediately after Ramen along the direction of travel: Ramen → Rabi.
"Bimal is between Rabi and Abir" makes Bimal a neighbour of both boys. Rabi already has Ramen on one side, so Bimal can only take Rabi's other side, and Abir sits just beyond Bimal: Ramen → Rabi → Bimal → Abir.
"Subrata is between Abir and Biman" makes Subrata a neighbour of both. Abir already has Bimal on one side, so Subrata takes Abir's other side and Biman follows Subrata: Ramen → Rabi → Bimal → Abir → Subrata → Biman.
All six boys are now placed, so Biman closes the ring back onto Ramen. Reading one step onward from Bimal along the direction of travel gives Abir, so Abir stands to the left of Bimal.
Cross-check. Written out as a closed ring, each boy’s two neighbours are:
Boy | On his left | On his right |
|---|---|---|
Ramen | Rabi | Biman |
Rabi | Bimal | Ramen |
Bimal | Abir | Rabi |
Abir | Subrata | Bimal |
Subrata | Biman | Abir |
Biman | Ramen | Subrata |
Every clue checks out against the ring: Rabi does sit on Ramen’s left, Bimal does sit between Rabi and Abir, and Subrata does sit between Abir and Biman. The result is also independent of which rotational sense one chooses to call "left": mirroring the whole circle swaps the two senses, but it relabels every clue at the same time, so Abir still ends up on Bimal’s left.