Question

15．洪林苗圃有柏樹(shù)350棵，柏樹(shù)的棵數(shù)是松樹(shù)的$\frac{1}{2}$，香樟樹(shù)的棵數(shù)是松樹(shù)的$\frac{5}{7}$．香樟樹(shù)有多少棵？

Answer 1

分析 先把松樹(shù)的棵數(shù)看作單位“1”，則松樹(shù)的棵數(shù)就是$\frac{1}{2}$，根據(jù)分?jǐn)?shù)除法的意義，用柏樹(shù)的棵數(shù)除以$\frac{1}{2}$就是松樹(shù)的棵數(shù)．再把松樹(shù)的棵數(shù)看作單位“1”，香樟樹(shù)的棵數(shù)是松樹(shù)的$\frac{5}{7}$，根據(jù)分?jǐn)?shù)乘法的意義，用松樹(shù)的棵數(shù)乘$\frac{5}{7}$就香樟樹(shù)的棵數(shù)．

解答 解：350÷$\frac{1}{2}$×$\frac{5}{7}$
=700×$\frac{5}{7}$
=500（棵）
答：香樟樹(shù)有500棵．

點(diǎn)評(píng) 此題是考查分?jǐn)?shù)乘、除法的意義及應(yīng)用．首先確定單位“1”，單位“1”所表示的量已知，用乘法解答，未知用除法解答．