Question

6．一個(gè)果園里，桃樹(shù)占$\frac{2}{5}$，梨樹(shù)和杏樹(shù)各占$\frac{1}{4}$，其余的是蘋果樹(shù)．桃樹(shù)、梨樹(shù)和杏樹(shù)共占總數(shù)的幾分之幾？蘋果樹(shù)占總數(shù)的幾分之幾？

Answer 1

分析 桃樹(shù)占$\frac{2}{5}$，梨樹(shù)和杏樹(shù)各占$\frac{1}{4}$，根據(jù)分?jǐn)?shù)加法的意義，將桃樹(shù)、梨樹(shù)及杏樹(shù)占總棵數(shù)的分率分別相加，即得桃樹(shù)、梨樹(shù)和杏樹(shù)共占總數(shù)的幾分之幾；將總棵數(shù)當(dāng)作單位“1”，根據(jù)分?jǐn)?shù)減法的意義，用單位“1”減去種的桃樹(shù)、梨樹(shù)和杏樹(shù)占總棵數(shù)的分率，即得蘋果樹(shù)占占總數(shù)的幾分之幾．

解答 解：$\frac{2}{5}$+$\frac{1}{4}$+$\frac{1}{4}$
=$\frac{13}{20}$+$\frac{1}{4}$
=$\frac{9}{10}$
1-$\frac{9}{10}$=$\frac{1}{10}$
答：桃樹(shù)、梨樹(shù)和杏樹(shù)共占總數(shù)的$\frac{9}{10}$，蘋果樹(shù)占總數(shù)的$\frac{1}{10}$．

點(diǎn)評(píng) 本題考查了學(xué)生完成簡(jiǎn)單的分?jǐn)?shù)加法與減法應(yīng)用題的能力．