8.28÷3＝2.76﹙分米﹚
3.14×﹙2.76÷2﹚²
＝3.14×1.8044
＝5.665816﹙分米²﹚
8.28－2.76＝5.52﹙分米﹚
5.665816×5.52≈31.3﹙分米³﹚
答∶油桶容积是31.3立方分米.