A rectangular box with volume 468 cubic feet is built with a square base and top. The cost is $1.50 per square foot for the top and the bottom and $2.00 per square foot for the sides. Let x represent the length of a side of rhe base in feet. Express the cost of the box as a function of X and then graph this function. From the graph find the value of x, to the nearest hundredth of a foot, which will minimize the cost of the box.