40 pieces of the same square wood can be piled into a cuboid 30 decimeters long, 20 decimeters wide and 15 decimeters high. How many cubic decimeters is the average volume of each square wood?
40 pieces, volume = 30 × 20 × 15 = 9000 cubic decimeter
Average volume of one piece = 9000 △ 40 = 225 cubic decimeter