The dimensions of the exterior of the (closed) shoebox are 6 by 7 by 4 inches. First find the surface area of the shoebox. To do this, you must find the surface area of one top, of one end and of one side. Then multiply all of these calculations by 2.
Total surface area = ?
Now divide the total surface area by (4 square inches per minute), to determine how many minutes it will take the kid to paint the whole exterior of the shoebox.