A trapezoidal channel has a depth of 10 ft and a bottom width of 100 ft. The side slopes are 2:1 (z = 2). Length ratios of Yr = 1/10 and Xr = 1/25 are selected. Determine the geometry of the model channel and the actual Rr. Calculate nm, using the actual Rr and compare with the assumption that Rr = Yr.