First find an equation for the volume of the trough. To do this you need to consider two separate areas, the rectangular one and the triangular one.
Volume of a rectangular box is LWH. Volume of a triangular box is 1/2BHL.
Can you do it from there?
I don't know if there is a limit to the amount you can post... I don't want to annoy anyone, but I'm having a hard time with these word problems...
A water trough is 10 feet long and has a cross-section that has the shape indicated in the attachment. If the trough is being filled with water at the rate of 1.25 ft cubed/minute, how fast is the water level rising when the water is 1.5 feet high?
First find an equation for the volume of the trough. To do this you need to consider two separate areas, the rectangular one and the triangular one.
Volume of a rectangular box is LWH. Volume of a triangular box is 1/2BHL.
Can you do it from there?
Assign a common variable between the two equations. Let's say that H is the height of water measured on the far left wall of your diagram. So the equation for the volume of the rectangular portion is 10*3*H, or 30H.
Now we need to do the same thing for the triangular portion. To do this we need to use similar triangles and Pythagoras. In your diagram there is a triangle of dimensions 0.5*2*x do you see this triangle?