Question

A rectangular pen is to be constructed with three equal sections. One side of the pen will be enclosed with the side of the barn. All other sides need to be fenced. If the total amount of fencing available is 510 feet, calculate the dimensions of each rectangular pen that would maximize the fenced area. State the maximum area as well. Show all work.

Answer 1

Let x be width and y = length of barn wall y + 2x =20Area = xy= x(20 - 2x)=20x -2x^2dA/dx = 20 - 4xmax at dA/dx =0 so 20 - 4x = 0x=5 y=10 max area is 50 sq ft