Pipes & Cisterns · Question 13 · Hard
Pipes & Cisterns question 13
Three taps A, B and C can fill a tank in 10, 12 and 15 hours respectively. All three are opened together, and after 2 hours B and C are closed. How many hours in total does it take to fill the tank?
- 5 hours
- 4 hours
- 6 hours
- 7 hours
Answer and explanation
Answer: D. 7 hours
Explanation: In the first 2 hours all three fill 2 × (6 + 5 + 4)/60 = 1/2. A alone fills the other 1/2 in 5 hours, so the total is 2 + 5 = 7 hours.
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