During a snowstorm the fluoride feeder in North Bend runs out of feed solution. As shown in Figure P-425, the rapid mix tank is connected to a 5-km long distribution pipe. The flow rate into the rapid mix tank is 0.44 m3 s1, and the volume of the tank is 2.50 m3. The velocity in the pipe is 0.17 m s1. If the fluoride concentration in the rapid mix tank is 1.0mgL1 when the feed stops, how long until the concentration of the fluoride is reduced to 0.01 mg L1 at the end of the distribution pipe? The fluoride may be considered a nonreactive chemical.