Paper I · 16 Logical Reasoning, Analytical Ability & Data Interpretation · 16.15 Logic puzzles and problem solving

16.15.2 Weighing, balances and counterfeit-coin puzzles

A two-pan balance has three outcomes (left down, right down, level), so each weighing can cut the suspects to one-third — which is why powers of 3 run through every counterfeit-coin and weights puzzle.

  • TGPSC MPSO / ASO · Paper I
  • Standard level
  • 7 min read
  • Full course

Key terms

  • balance puzzle
  • counterfeit coin
  • fake coin
  • minimum weighings
  • powers of 3
  • powers of 2
  • weights on both pans
  • fake bag puzzle
  • balance equations
  • heaviest and lightest
  • twelve coins

What this note covers

  1. Core factsFoundation
  2. ExplainedStandard
  3. DeeperAdvanced
  4. Common trapsFoundation
  5. Quick revisionFoundation

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