又有数学问题，大神再再再再进！

又有数学问题，大神再再再再进！

（6/2）的平方×3.14×5=141.3（立方米）
141.3×0.8=113.04（吨）
解：油桶的高为：
4×3=12（分米）；
（1）油桶的侧面积：
2×3.14×4×5=125.6（平方分米）；
水桶的底面积：
3.14×42×2
=3.14×16×2，
=100.48（平方分米）；
水桶的表面积：
125.6+100.48=226.08≈227（平方分米）；
答：制作这个油桶至少需要227平方分米铁皮．

（2）3.14×42×12，
=3.14×16×12，
=602.88（立方分米），
=602.88（升）．
答：这个油桶的容积是602.88升追问一根圆柱型木料长40分米，锯下5分米的一段后，剩下的木料比原来木料的表面积减少94.2平方分米。原来这根木料的体积是多少？追答底面周长 94.2÷5＝18.84
半径18.84÷（2x3.14）=3dm
体积 3x3x3.14x40=1130.4立方分米

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