• A pipe can fill a tank in 10 h, while an another pipe can empty it in 6 h. Find the time taken to empty the tank, when both the pipes are opened up simultaneously.
 A) 11 h B) 15 h C) 18 h D) 16 h

 B) 15 h

Part filled by 1st pipe in 1 h = $$\Large \frac{1}{10}$$

Part emptied by 2nd pipe in 1 h = $$\Large \frac{1}{6}$$

Part emptied when both the pipes are opened up

= $$\Large \frac{1}{6}$$ - $$\Large \frac{1}{10}$$ = $$\Large \frac{5-3}{30}$$=$$\Large \frac{2}{30}$$=$$\Large \frac{1}{15}$$

Hence, time taken to empty the full tank in 15 h.

Similar Questions
1). Three taps are fitted in a cistern. The empty cistern is filled by the first and the second taps in 3 and 4 h, respectively. The full cistern is emptied by the third tap in 5 h. If all three taps are opened simultaneously, the empty cistern will be filled up in
 A). $$\Large 1\frac{14}{23}$$ B). $$\Large 2\frac{14}{23}$$ C). 2 h 40 min D). 1 h 56 min
2). Pipe A can fill a tank in 30 min, while pipe B can fill the same tank in 10 min and pipe C can empty the full tank in 40 min. If all the pipes are opened together, how much time will be needed to make the tank full?
 A). $$\Large 9\frac{3}{13}$$ h B). $$\Large 9\frac{4}{13}$$ h C). $$\Large 9\frac{7}{13}$$ h D). $$\Large 9\frac{9}{13}$$ h
3). Pipes A and B can fill a tank in 5 and 6 h, respectively. Pipe C can fill it in 30 h. If all the three pipes are opened together, then in how much time the tank will be filled up?
 A). $$\Large 3\frac{3}{14}$$ h B). $$\Large 2\frac{1}{2}$$ h C). $$\Large 3\frac{9}{14}$$ h D). $$\Large 2\frac{1}{14}$$ h
4). Through an inlet, a tank takes 8 h to get filled up. Due to a leak in the bottom, it takes 2 h more to get it filled completely. If the tank is full, how much time will the leak take to empty it?
 A). 16 h B). 20 h C). 32 h D). 40 h
5). A tap can fill an empty tank in 12 h and a leakage can empty the tank in 20 h. If tap and leakage both work together, then how long will it take to fill the tank?
 A). 25 h B). 40 h C). 30 h D). 35 h
6). Three taps A, B and C together can fill an empty cistern in 10 min. The tap A alone can fill it in 30 min and the tap B alone can fill it in 40 min. How long will the tap C alone take to fill it?
 A). 16 min B). 24 min C). 32 min D). 40 min
 A). $$\Large 8\frac{1}{4}$$ B). $$\Large 8\frac{3}{4}$$ C). 5 min D). $$\Large 8\frac{1}{2}$$
8). There are three pipes connected with a tank. The first pipe can fill $$\Large \frac{1}{2}$$ part of the tank in 1 h, second pipe can fill $$\Large \frac{1}{3}$$ part of the tank in 1 h. Third pipe is connected to empty the tank. After opening all the three pipes, $$\Large 7\frac{1}{2}$$ part of the tank can be filled in 1 h, then how long will third pipe take to empty the full tank?