Pipes & Cisterns · Question 22 · Medium
Two pipes together fill a tank in 6 hours. Alone, pipe A takes 5 hours less than pipe B. How long does pipe A alone take to fill the tank?
- 15 hours
- 10 hours
- 12 hours
- 9 hours
Answer and explanation
Answer: B. 10 hours
Explanation: If A takes a hours, then 1/a + 1/(a + 5) = 1/6, giving a² − 7a − 30 = 0, so a = 10 (the other root is negative). A takes 10 hours and B 15 hours.
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