Subject: General Aptitude · Chapter: Pipes and Cisterns · Exam: 2004 · Marks: · Difficulty:
Pipes A and B can fill a tank in 20 hours and 30 hours respectively and pipe C can empty the full tank in 40 hours. If all the pipes are opened together, how much time will be needed to make the tank full?
(a)$10 \frac{3}{7}$ hours
(b)$12 \frac{4}{5}$ hours
(c)$17 \frac{1}{7}$ hours
(d)$19 \frac{1}{4}$ hours
Answer
Answer (as printed): C
Explanation
Net part filled in 1 hour = + − = . 20 30 40 120 120 1 ∴ The tank will be full in i.e. 17 hours. 7 7 1 1 1 1 17 19
Explanation as extracted from the printed page; notation may be imperfect.