Water at 20 C flows steadily through a tank, entering at a volumetric flow rate of 100 m/hr through a 6 cm diameter inlet, and exiting with an average velocity of 8 m/s through a 5 cm diameter outlet. A third opening on the tank, with 4 cm diameter, may act as an inlet or outlet for water flow. Determine (a) the volumetric flow rate in m/hr in or out of the tank at this third opening, and (b) the corresponding average velocity in m/s.