Question

A trough is 12 ft long and its ends have the shape of isosceles triangles that are 5 ft across at the top and have a height of 1 ft. If the trough is being filled with water at a rate of 13 ft3/min, how fast is the water level rising when the water is 8 inches deep?
I have been getting 13/30, but apparently, that is wrong?

V=.5 * h * l * b

Because of similar triangles:
b = 5h (b/h = 5/1)
l = 12

V = .5 * h * 5h * 12
V = 30h^2
(dV/dt) = 60 h (dh/dt)

dV/dt = 13
h = .5 (because this is in feet)

13 = 60*.5(dh/dt)
13/30 = dh/dt

Answer 1

Im confused can u teach me how to do this stuff