Final answer:
To calculate the amount of fencing material needed to surround the pen, we use the formula for the perimeter of a rectangle and find the dimensions of the rectangle using the given area.
Step-by-step explanation:
To find the amount of fencing material needed to surround the pen, we need to calculate the perimeter of the pen. Since the pen is in the shape of a rectangle, we can use the formula for the perimeter of a rectangle: Perimeter = 2(length + width).
In this case, the area of the pen is given as 400 ft², so we need to find the dimensions of the rectangle. Since the area of a rectangle is calculated as Area = length x width, we can set up an equation to solve for the dimensions: length x width = 400.
Once we have the dimensions, we can substitute them into the perimeter formula to find the amount of fencing material needed.