If the unit of displacement of the outlet pipe in one minute is 1, the displacement of the first case is 1×2×8= 16, and that of the second case is 1×3×5= 15, and the difference between the two cases is/kloc-0. In the first case, during the drainage period, * * * water inflow is 1/3 ×8=8/3, so before the drainage starts, the water inflow in the pool is 16-8/3=40/3, and the water inflow time is required (that is, the outlet pipe is later than the inlet pipe): 40/3.