A 4-m-high cylindrical tank having a cross-sectional area of A_T = 1.5 m² is filled with equal volumes of water and oil whose specific gravity is SG = 0.75. Now a 1-cm-diameter hole at the bottom of the tank is opened, and water starts to flow out. If the discharge coefficient of the hole is C_d = 0.85, determine how long it will take for the water in the tank, which is open to the atmosphere to empty completely.