There is a trough that is 7 feet long, and its vertical cross sections are inverted isosceles triangles with a height 5 feet and base 2 feet. There is water in it and and the water is being siphoned out at the rate of 3 cubic feet per minute. At any time t, let d be the depth and V be the volume of the water in the trough.
1. Find the volume of the trough when its full.
2. What is the rate of change in the area of the surface of the water at the instant when the trough is .25 full by volume?