📚 RRB Railway – Reasoning
Seating Arrangement – Study Notes
1. Simple Explanation
Seating arrangement problems test your ability to deduce the relative positions of people/items based on a set of clues.
- Objects: People, seats, trains, compartments, etc.
- Positions: Left, Right, Ahead, Behind, Adjacent, Between, etc.
- Constraints: “A is never next to B”, “C sits two seats to the right of D”, “E sits somewhere between F and G”, etc.
The goal is to create a consistent arrangement that satisfies all given clues.
Tip: Treat the arrangement as a puzzle where each clue is a rule you must obey.
2. Key Points & Strategies
| # | Strategy | Why it Works | How to Apply |
|---|---|---|---|
| 1 | Draw a Grid/Diagram | Visual representation reduces confusion. | Make a row/column table and mark positions as you deduce. |
| 2 | List All Entities | Keeps track of who is who. | Create a list of all people/objects and tick off when placed. |
| 3 | Use “Between” & “Adjacent” Clues First | These often give fixed distances. | If “X is between Y and Z” and you know Y & Z positions, place X accordingly. |
| 4 | Apply “Never Next To” Rules Early | Prevents contradictory placements. | If A cannot be next to B, mark forbidden spots around A. |
| 5 | Work In Reverse | Start from a known position and back‑track. | If “F sits at the far left”, start from there and work rightwards. |
| 6 | Check Consistency After Every Placement | Avoids later contradictions. | After placing someone, verify all clues still hold. |
| 7 | Use Logical Deduction | Some clues leave only one possibility. | If “G is somewhere to the right of F” and only one seat remains to the right, place G. |
| 8 | Consider All Options When Stuck | Explore alternative placements. | Draw two separate diagrams for each possibility. |
3. Worked Example
Problem
In a train carriage, 7 passengers – A, B, C, D, E, F, G – are seated in a row of 7 seats.
Clues
- A sits in the middle seat.
- B sits to the left of A.
- E sits somewhere between B and C.
- D sits two seats to the right of C.
- F sits immediately to the right of D.
- G sits on the far right end.
Question: Arrange the passengers.
Step‑by‑Step Solution
| Step | Action | Reasoning |
|---|---|---|
| 1 | Seat A in the middle (seat 4). | Clue 1. |
| 2 | Place B to the left of A, but not next to A yet. | Clue 2 – could be seat 1, 2, or 3. |
| 3 | Seat G on the far right (seat 7). | Clue 6. |
| 4 | Place C somewhere right of B but left of E (Clue 3). | C must be between B & E. |
| 5 | D is two seats to the right of C (Clue 4). | D = C + 2 seats. |
| 6 | F sits immediately right of D (Clue 5). | F = D + 1 seat. |
| 7 | Test possibilities for B: try seat 3. | If B=3 → C must be >3 and <E. |
| 8 | With B=3, we have seats left: 1,2,5,6. | C must be >3; only seat 5 works. |
| 9 | Place C at seat 5. | satisfies “between B & E” (E will be >5). |
| 10 | D = C+2 → seat 7 (already G). Contradiction. | So B≠3. |
| 11 | Try B=2. | Now seats left: 1,3,5,6. |
| 12 | Place C somewhere >2 and <E. | C could be seat 3 or 5. |
| 13 | If C=3 → D=5, F=6. | Check remaining seat 1 for E. E would be left of C (contradict). |
| 14 | So C=5. | D=7 (occupied by G) → contradiction. |
| 15 | B=1? | Then C must be >1, <E. |
| 16 | Try C=3. | D=5, F=6. |
| 17 | Remaining seat 2 for E. | E sits between B(1) and C(3) ✔️ |
| 18 | All clues satisfied. | ✔️ |
| Seat | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
|---|---|---|---|---|---|---|---|
| Person | B | E | C | A | D | F | G |
Final arrangement: B – E – C – A – D – F – G
4. Quick Revision Summary
| Topic | Key Takeaway |
|---|---|
| Position Terms | Left/Right/Front/Back, Adjacent, Between, Far Left/Right, Middle, Immediate |
| Common Constraints | “Never next to”, “Somewhere between”, “Exactly 1 seat apart”, “Exactly 2 seats apart” |
| Diagramming | Use a numbered row/column grid; mark fixed seats immediately |
| Logical Flow | Start with absolute clues → use “between” → place relative ones → fill gaps |
| Consistency Check | After each placement, re‑ |