Question. Pipes A and B can fill a tank in 5 and 6 hours respectively. Pipe C can empty it in 12 hours. If all the three pipes are opened together, then the tank will be filled in?
  1. 1 13/17 hours
  2. 2 8/11 hours
  3. 3 9/17 hours
  4. 4 1/2 hours