Question

12．一個(gè)果園，梨樹(shù)占$\frac{1}{3}$，桃樹(shù)和蘋(píng)果樹(shù)各占$\frac{1}{4}$，其余的是杏樹(shù)．
請(qǐng)你提出數(shù)學(xué)問(wèn)題并只列式不解答．
①問(wèn)題：梨樹(shù)、桃樹(shù)和蘋(píng)果樹(shù)一共占果園的幾分之幾？列式：$\frac{1}{3}+\frac{1}{4}+\frac{1}{4}$
②問(wèn)題：梨樹(shù)比桃樹(shù)多占果園的幾分之幾？列式：$\frac{1}{3}-\frac{1}{4}$
③問(wèn)題：杏樹(shù)占果園的幾分之幾？列式：1-（$\frac{1}{3}+\frac{1}{4}$）．

Answer 1

分析 把果園的面積看作單位“1”．根據(jù)分?jǐn)?shù)加減法的意義，可以提分?jǐn)?shù)的加減法問(wèn)題．
①問(wèn)題：梨樹(shù)、桃樹(shù)和蘋(píng)果樹(shù)一共占果園的幾分之幾？用加法計(jì)算．
②問(wèn)題：梨樹(shù)比桃樹(shù)多占果園的幾分之幾？用減法計(jì)算．
③問(wèn)題：杏樹(shù)占果園的幾分之幾？用單位“1”減去梨樹(shù)、桃樹(shù)和蘋(píng)果樹(shù)一共占果園的幾分之幾即可解答．

解答 解：①問(wèn)題：梨樹(shù)、桃樹(shù)和蘋(píng)果樹(shù)一共占果園的幾分之幾？
$\frac{1}{3}+\frac{1}{4}+\frac{1}{4}$
=$\frac{1}{3}+\frac{1}{2}$
=$\frac{5}{6}$
答：梨樹(shù)、桃樹(shù)和蘋(píng)果樹(shù)一共占果園的$\frac{5}{6}$．

②問(wèn)題：梨樹(shù)比桃樹(shù)多占果園的幾分之幾？
$\frac{1}{3}-\frac{1}{4}=\frac{1}{12}$
答：梨樹(shù)比桃樹(shù)多占果園的$\frac{1}{12}$．

③問(wèn)題：杏樹(shù)占果園的幾分之幾？
1-$\frac{5}{6}=\frac{1}{6}$
答：杏樹(shù)占果園的$\frac{1}{6}$．
故答案為：梨樹(shù)、桃樹(shù)和蘋(píng)果樹(shù)一共占果園的幾分之幾，$\frac{1}{3}+\frac{1}{4}+\frac{1}{4}$；梨樹(shù)比桃樹(shù)多占果園的幾分之幾，$\frac{1}{3}-\frac{1}{4}$；杏樹(shù)占果園的幾分之幾，1-（$\frac{1}{3}+\frac{1}{4}$+$\frac{1}{4}$）．

點(diǎn)評(píng) 本題要從分?jǐn)?shù)加減法的意義來(lái)提問(wèn)題，要把果園的面積看作單位“1”．