Unit 14
Ordering Deduction
About this unit
Place people, objects, or events in the correct order — or determine what must, could, or cannot be in a specific position — using a set of positional clues. Questions range from simple 4-person linear arrangements to complex 8-person circular seating, relay handovers, and multi-criteria ranking puzzles.
What types of questions will you face?
- 1Linear ordering: 4-6 people in a row with "left of", "right of", and "not at end" constraints
- 2Circular seating: 6-8 people around a table with "opposite", "adjacent", and relative-direction constraints
- 3Relay/handover chain: trace an object passing through a sequence of handovers at specific times
- 4Multi-criteria ranking: rank people by two criteria simultaneously (time AND score) using clues
- 5Partial ordering: given 3 facts about relative positions, determine what else MUST or CANNOT be true
- 6"Valid arrangement" questions: given 4 possible orderings, identify the one that satisfies all rules
Skills you will build
- Tracking multiple positional constraints (before/after, adjacent, not adjacent) simultaneously
- Building up valid arrangements step-by-step from the most constrained element first
- Applying "opposite in a circle" and "adjacent" rules for circular arrangements
- Tracing relay handover chains forward in time
- Determining what must be true vs. what could be true when the arrangement isn't fully fixed
- Using elimination to discard invalid arrangements quickly
By the end of this unit, you will be able to
- Solve any 4-8 person linear or circular arrangement puzzle
- Trace relay chains across time to find who holds an item at any point
- Determine fixed positions and free positions in a partially constrained arrangement
- Answer "must be true / cannot be true" ordering questions reliably under time pressure
Difficulty profile
The hardest unit by average score (3.82). Simple 3-4 element orderings with one chain are Easy; circular arrangements with 6-8 people and multiple constraint types, relay chains, and multi-criteria rankings are Very Difficult. Mastery here significantly boosts your overall TS score.
Exam tip: Ordering Deduction
Start with the person/item with the most constraints — they are easiest to place. Then use each placed element to constrain the remaining ones. For circular arrangements, fix one person's seat first (the one with a "directly opposite" clue) then fill in from there.
Sample Questions
Five-person ordering puzzles look dense, but one fixed clue (who is last) plus a locked pair (who is immediately before whom) usually collapses the grid quickly.
Multi-clue arrival-order questions sit in the harder stretch of Selective TS — the same anchors recur: last/first, before/after chains, “immediately before”, and “not first”.
You must satisfy every constraint at once: a fixed position, relative chains, a consecutive pair treated as one block, and an exclusion — then read off the requested position.
Five people arrive (or finish) one at a time. Clues mix fixed ends, order chains, adjacency, and “not first”. You find who occupies a specific position (often 2nd or 3rd).
Best approach: Anchor the definite slot (e.g. Eva last = 5th). Place the [Dee][Ana] block in legal positions using “Dee not first”. Chain Cal → Ben → Eva, then fill the only consistent grid.
Question
Five students arrive at a competition one at a time — no two arrive at the same moment. Their names are Ana, Ben, Cal, Dee, and Eva.
- Eva arrives last.
- Ben arrives before Eva but after Cal.
- Dee arrives immediately before Ana (no one between them).
- Dee does not arrive first.
- Ana arrives before Ben.
Who arrives second?
- ADee
- BAna
- CCal
- DBen
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Relay questions are chain puzzles: trace who holds the object after each meeting, find the broken link, then pick the one extra handover that fixes the timing.
Handover-chain items appear in the medium band of Selective TS — reliable marks when you draw the timeline instead of guessing which names “sound right”.
The examiner checks whether you can map a delivery chain forward, spot who never receives the item, and reject options where the sender does not yet have it or the meeting is too late.
An item must reach a final person via scheduled meetings. One link between the current holder and the next leg is missing. You choose which extra meeting completes the chain today.
Best approach: Sketch A → B → ? → … → Z with times. Mark who has the object after each step. The fix must pass the item from the current holder to the next person before their downstream meeting.
Question
Nia must return a tablet to Omar today. She will not see Omar in person. These handovers will happen:
- Nia gives the tablet to Pia at 08:30.
- Quinn meets Ravi at 09:30.
- Ravi meets Sara at 10:30.
- Sara meets Omar at 11:45.
Which one extra meeting, if added, could allow Omar to receive the tablet today?
- AOmar meets Quinn at 08:00.
- BPia meets Ravi at 10:00.
- CNia meets Omar at 07:45.
- DPia meets Quinn at 11:00.
Decided on your answer? Check how you went below.
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