railway RRB NTPC Mock Test Series 2024-25 (CBT 1 + CBT 2) Quantitative Aptitude Time and Work Pipe and Cistern
Out of three pipes the first two can fill an empty tank in 9 hours and 18 hours, respectively while the third can drain the filled tank in 15 hours. If all the three pipes are opened when the tank is empty, after how many hours will the tank be full?
1
10
2
12
3
11
4
13