Atrough is 14 ft long and its ends have the shape of isosceles triangles that are 2 ft across at the top and have a height of 1 ft. if the trough is being filled with water at a rate of 8 ft3/min, how fast is the water level rising when the water is 9 inches deep?

The question is asking to calculate how fast is the water level rising when the water is 9 inches deep and base on the said question or problem, and in my own understanding and computation about the said problem, the speed of the rising of the water level is 24/63 feet per minute. I hope this would help