A tank is initially empty. Inlets A, D, and E are opened one after another for one hour each and then closed. After that, outlet Z is opened to empty ...
Question
A tank is initially empty. Inlets A, D, and E are opened one after another for one hour each and then closed. After that, outlet Z is opened to empty the tank. Given that inlet A fills the tank in 4 hours, inlet D in 2 hours, inlet E in 2 hours, and outlet Z empties the tank in 30 hours, how long (in hours) will outlet Z take to empty the tank completely?