A section of straight tube with an inner diameter of 10 cm serves as a mixing device. There are two inflows at one end - one through a concentric tube of 5 cm inner diameter (and 6 cm outer diameter) and the other through the annular egion between the two tubes - and a single outflow of the mixed fluids at the other end. If the average outflow velocity is 5m/sec and the average inflow velocity in the annular region is 3m/sec, what is the average inflow velocity in the concentric central tube? Assume the fluids have the same constant density.