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HKIMO 2026 Grade 9 National Preliminary Set 04 Question 22

HKIMO · HKIMO 2026 Grade 9 National Preliminary Set 04

Question 22

A box has three black, four blue and five red balls. In how many ways can three balls be drawn simultaneously with exactly one blue ball?

Editorial counting convention: distinguish the individual physical balls, including balls of the same colour.
  1. 112
  2. 224
  3. 60
  4. 110