Question

Pipes A and B can fill a tank in 5 and 6 hours respectively. Pipe C can empty it in 12 hours. The tank is half full. All the three pipes are in operation simultaneously. After how much time will the tank will be full?​

Answer 1

Answer:

1 13/7 hours.

Step-by-step explanation:

Part of the tank filled in one hour =  5 1 ​  +  6 1 ​  −  12 1 ​                                                            =  12+10−5/60 ​  =  17/60 ​   of the tank is filled  

Therefore,  1/2 ​   of the tank is filled in   60/17 ​  ×  1/2 = 30/17 ​   hours =1  17 /13 ​   hours.