A tank can be filled by pipe A in 20 minutes and by pipe B in 30 minutes. If both pipes are opened together, how long will it take to fill the tank?
- A.10
- B.12 ✓
- C.15
- D.18
Explanation: Combined rate = 1/20+1/30 = 5/60 = 1/12 of the tank per minute, so it takes 12 minutes.
Class 6 IMO Mathematics Olympiad practice · HOTS / Achievers · Multi-Concept Achievers
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