Order and Ranking
About 6 min · Reasoning Ability · English
Time worked out from the lesson's 401 words at 150 words a minute, plus a minute for each question.
The concept is straightforward: you're given information about a person's position in a row, queue, or list (from top/bottom, left/right, or both ends), and you must determine total count, exact position, or number of persons between two individuals.
Key ideas
- Single-direction position: When only one position (from left/top OR right/bottom) is given, you cannot determine total count without additional information.
- Dual-direction relationship: Total = Position from Left + Position from Right − 1. This works because the person is counted in both positions, so we subtract 1 to avoid double-counting.
- Position interchange: When two people swap places, their NEW positions become each other's OLD positions. Track carefully what changes and what stays constant.
- Persons between two individuals: If Person A is at rank X and Person B is at rank Y (where X < Y), then persons between them = Y − X − 1.
- Same position from both ends: If a person's rank from top equals rank from bottom, then Total = 2 × Rank − 1 (the person sits exactly in the middle).
Watch out for
- Forgetting to subtract 1: Students often add both positions without subtracting 1, double-counting the person. → Always apply: Total = Left + Right − 1.
- Confusing "between" with "including": If asked "how many between A and B," don't count A and B themselves. → Between = |Difference| − 1.
- Misreading interchange problems: After interchange, each person takes the OTHER's position, not some new position. → Track: A goes to B's spot, B goes to A's spot.
Quick reference
- Total = Left Position + Right Position − 1
- Between A and B = |Position A − Position B| − 1
- Convert Right to Left: Left Position = Total − Right Position + 1
- Interchange: A's new spot = B's old spot (and vice versa)
- Same rank from both ends means person is in exact middle
Check yourself: 3 questions
1. In a class of 45 students, Rohan's rank from the top is 12th. What is his rank from the bottom?
2. In a row of children facing North, Priya is 15th from the left end and Vijay is 18th from the right end. If they interchange their positions, Priya becomes 28th from the left end. How many children are there in the row?
3. Amit ranks 7th from the top and 28th from the bottom in a class. How many students are there in the class?
This lesson is cut from the topic's note, not rewritten. Fact-checked on 18 Oct 2026: an AI-assisted check of this note against cited sources; the errors it found were corrected that day. Some errors may remain. The questions are from Shishya's validated question bank.
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