A cylindrical concrete silo of 6 m internal diameter and 24 m height is filled with rough rice having bulk density of 635 kg.m^-3. The angle of friction between concrete wall and rough rice is 30°. The ratio between lateral and vertical pressure is 0.4. The ratio of lateral pressure at 10 m depth to the 5 m depth is ______ (Rounded off to 2 decimal places)