If the viscosity of ground water is 1.00, the Slitcher's constant is 400, the effective size of soil particles in acquifer is 0.5 mm and hydraulic gradient is 1 in 80, the velocity of flow is

• 0.25 m/day
• 0.50 m/day
• 0.75 m/day
• 1.00 m/day
• 1.25 m/day.