3. Pipes A and B can fill a tank in 5 and 6 hours respectively,Pipe C

1.	3. 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 thethree pipes are in operation simultaneously. After how much timethe tank will be full?
Answer» Pipes A and B can fill the tank in 5 and 6 hours respectively. Therefore,part filled by pipe A in 1 hour=1/5 part filled by pipe B in 1 hour =1/6 Pipe C can empty the tank in 12 hours. Therefore,part emptied by pipe C in 1 hour=1/12 Net part filled by Pipes A,B,C together in 1 hour=1/5+ 1/6 −1/12=17/60 i.e., the tank can be filled in60/17=3(9/17) hours

3. 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 thethree pipes are in operation simultaneously. After how much timethe tank will be full?

Answer»

Pipes A and B can fill the tank in 5 and 6 hours respectively. Therefore,part filled by pipe A in 1 hour=1/5

part filled by pipe B in 1 hour =1/6

Pipe C can empty the tank in 12 hours.

Therefore,part emptied by pipe C in 1 hour=1/12

Net part filled by Pipes A,B,C together in 1 hour=1/5+ 1/6 −1/12=17/60

i.e., the tank can be filled in60/17=3(9/17) hours