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Engineering Exam Notes

Ranking, Ordering & Inequalities Notes

Questions

3 questions per paper

Difficulty

Medium

Importance

High yield for HPCL/NTPC/ONGC

Overview

Ranking, Ordering, and Inequalities assess logical reasoning by testing your ability to determine relative positions and relationships within a group. Mastery of these concepts is essential for PSU exams as they provide quick-win marks through structured pattern analysis and methodical elimination.

Linear Ranking Fundamentals

Linear ranking involves determining the position of an individual in a row based on given constraints from the left, right, top, or bottom. You must accurately account for whether the target person is included in the counting sequence to avoid off-by-one errors.

  • Total = (Rank from Left + Rank from Right) - 1
  • Rank from Left = Total - Rank from Right + 1
  • Number of persons between two ranks = |Rank A - Rank B| - 1
  • When positions are interchanged, equate the new rank to the old rank to find the total

Mathematical Inequalities

This section tests your ability to deduce relationships between variables using symbols like greater than, less than, and equal to. Focus on identifying 'definite' versus 'possible' conclusions by checking if the inequality sign is consistent throughout the chain.

  • If paths are blocked (conflicting signs like > and <), no conclusion can be drawn
  • A > B ≥ C implies A > C is definitely true
  • A = B ≥ C implies A ≥ C is definitely true
  • Either/Or case occurs when two elements have three possible relations (>, <, =)

Circular and Double Row Arrangements

Circular arrangements add a layer of complexity by requiring you to track relative positions based on center-facing or outward-facing orientations. Double row problems often involve matching individuals from one row to another based on shared constraints.

  • Right movement in a circle is anti-clockwise if facing inward
  • Left movement in a circle is clockwise if facing inward
  • Always fix one person first to act as a reference point in circular problems
  • For double rows, draw parallel lines and use arrows to map relations between row members

Formula Sheet

Total = Left + Right - 1

Between = |Rank 1 - Rank 2| - 1

Total = Top + Bottom - 1

Exam Tip

For inequality questions, scan the required conclusion first to quickly identify which path of operators to trace, saving time by ignoring irrelevant variables.

Common Mistakes

  • Forgetting to subtract 1 when calculating the total number of people in a linear row.
  • Assuming the 'Either/Or' condition applies without checking if both individual conclusions are false.
  • Confusing left/right orientation when the problem statement mentions people facing the opposite direction.

More Revision Notes

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