A water trough is 5m long and has a cross-section in the shape of an isosceles trapezoid that is 20 cm wide at the bottom, 60 cm wide at the top, and has height 40 cm. If the trough is being filled with water at the rate of 0.2 m3/min how fast is the water level rising when the water is 20 cm deep? Possibly 0.2 / (1.8 + 0.5) = .0869m? But WebAssign doesn't accept fraction the 0.2/2.3. Before I try .0869m I want to see the right answer and how you got there.