A rectangular cow pasture is enclosed on three sides by a fence and the fourth side is part of the side of a barn that is 400 feet long. The fence costs $5 per foot, and $1200 altogether. To the nearest foot, find the length of the side parallel to the barn that will maximize the area of the pasture.
For any quadrilateral, the greatest ratio of area to perimeter is when the quadrilateral is a square.
The total length of fence which will form the three sides is 240 ft . . . obtained by (1200 $) / (5 $ / ft)
Each of the fence sides will be 80 ft (1/3 of 240), the side of the fence parallel to the barn will be 80 ft
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