The pool is provided with a water inlet and a water outlet. Open the water inlet pipe first, and then open the water outlet pipe after some water is stored in the pool. If two outlet pipes are opened at the same time, the pool can be emptied in 8 minutes; If three outlet pipes are opened at the same time, the pool can be emptied in five minutes. How many minutes does the outlet pipe open later than the inlet pipe?

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.