A package in the shape of a rectangular box can be mailed by the us postal service if the sum of its length and girth (the perim
eter of a cross-section perpendicular to the length) is at most 108 in. find the dimensions of the package with largest volume that can be mailed. (for full cr
For a given girth, the largest area will be that of a square. Then for some length x, the volume will be .. V = x((108 -x)/4)^2 .. = (1/16)*x*(108 -x)^2 The largest volume will be found where the derivative of this with respect to x is zero. .. V' = (1/16)*((108 -x)^2 -2x(108 -x)) .. 0 = (108 -x)(108 -x -2x) .. x = 108 or 108/3 = 36
The dimensions of the largest package that can be mailed are .. 36 inches in length and 72 inches in girth