The answer is 4.953 I don't understand how you would use a table sorry.
W=width of the pasture, and
<span>320000/w=length (parallel to river) </span>
<span>F=twice width + length </span>
<span>=2w + 320000/w </span>
<span>Find derivative of F with respect to w and equate to zero to find w. </span>
<span>i.e. </span>
<span>Solve for w in </span>
<span>dF/dw=0
hope it helps</span>