Flow depth and bed slope of a wide rectangular alluvial canal are 3.8 m and 1.5 × 10^-4 respectively. The velocity is found out to be 1.9 m/s. The mean size of the sediment particles is 1.6 mm. What is the ratio (corrected up to three decimal point) of rugosity coefficient given by Strickler’s formula to the actual rugosity coefficient?