Solution:
The area of fence needed is the area of the upper pyramid plus the area of the square prism. That is:
the area of a Pyramid is given by the following formula:
and the area of the rectangular prism is:
A = 2lw +2lh+2wh
where
l is the lenght, h is the height and w is the width
Thus, using the data from the problem and the equations above, we can conclude that:
so that, the correct answer is: