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📐 Mathematics  ·  Probability (Class 11)  ·  JEE

When two dice are rolled, why is treating (2, 3) and (3, 2) as a single outcome an error?

Answer: The two dice are distinguishable, so the resulting 21 unordered pairs are not equally likely.

  • A Unordered pairs are correct, but the arithmetic becomes harder to manage
  • B The two dice are distinguishable, so the resulting 21 unordered pairs are not equally likely
  • C Ordered pairs are only used when the dice have different numbers of faces
  • D The sample space must always contain exactly 36 elements by definition

Correct answer: B. The two dice are distinguishable, so the resulting 21 unordered pairs are not equally likely

Explanation: Each ordered pair has probability 1/36, so an unordered pair like {2,3} has probability 2/36 while {4,4} has only 1/36 - collapsing them breaks the equally-likely assumption.

Concept context

Random experiments, sample space, events, and the axiomatic approach to probability

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