Pipes A and B can fill a tank in 9 and 6 hours respectively. Pipe C can empty it in 18 hours. If all the three pipes are opened together, then the tank will be filled in?  Choose the correct choice from the following options:  A) 3 9/97 hrs  B) 4 2/4 hrs  C) 3 9/17 hrs  D) 3 9/27 hrs  E) 3 9/19 hrs
Net part filled in 1 hour = 1/9 + 1/6 - 1/18   = 4/18   The tank will be full in 18/4 hrs, i.e., 4 2/4 hrs.   Answer:4 2/4 hrs
<result>B</result>
Pipes A and B can fill a tank in 9 and 6 hours respectively. Pipe C can empty it in 18 hours. If all the three pipes are opened together, then the tank will be filled in?