Answer:
Width = 166.7 ft
Length = 250 ft.
Step-by-step explanation:
From the diagram at the ATTACHMENT
Let us denote the the length of the rectangular area as "x" and
the width of the rectangular area as "y"
Since, cost of the fence on the western side is shared with a neighbor, we can say it is $7 per foot. Otherwise, it is $14 per foot. The northern length is not fenced.
From the question, we know that the cost is not to exceed $7000, therefore we can expressed it as
7y + 14x + 14y = 7000
14x + 21y = 7000
Divide through by 14, we have
(x + 1.5) = 500 ------------- eqn (*)
But the area of the fenced
= A = (x×y) -------------- eqn (**)
Substitute (*) into (**) we have
A = (500 - 1.5y)*y
= 500y - 1.5y²
In other to maximize the Area, we can find the differential of A
A'(y) = 500 - 3y
At A'(y) = 0.
500-3y= 0
3y=500
y= 166.67 ft
From eqn(*)
(x+ 1.5) = 500
x = 500 - 1.5y
500-1.5(166.67)
= 250ft
Therefore, the dimensions for the plot that would enclose the most area are
Width of 166.67 ft and Length = 250 ft.
