Question

20．果園里桃樹(shù)與梨樹(shù)的棵數(shù)之比是5：4，桃樹(shù)棵樹(shù)比梨樹(shù)多25%，梨樹(shù)棵樹(shù)比桃樹(shù)少20%，桃樹(shù)是它們總棵數(shù)的55.6%．

Answer 1

分析 在這里把桃樹(shù)的棵數(shù)看作5，則梨樹(shù)的棵數(shù)就是4．求桃樹(shù)比梨樹(shù)多百分之幾，把梨樹(shù)的棵數(shù)看作單位“1”，用桃樹(shù)比梨樹(shù)多的棵數(shù)除以梨樹(shù)的棵數(shù)；
求梨樹(shù)比桃樹(shù)少百分之幾，把桃樹(shù)的棵數(shù)看作單位“1”，用梨樹(shù)比桃樹(shù)少的棵數(shù)除以桃樹(shù)棵數(shù)；
求桃樹(shù)是它們總和棵數(shù)的百分之幾，把總棵數(shù)看作單位“1”，用桃樹(shù)棵數(shù)除以總棵數(shù)．

解答 解：（5-4）÷4
=1÷4
=25%
（5-4）÷5
=1÷5
=20%
5÷（5+4）
=5÷9
≈55.6%
即果園里桃樹(shù)與梨樹(shù)的棵樹(shù)之比是5：4，桃樹(shù)棵樹(shù)比梨樹(shù)多25%，梨樹(shù)棵樹(shù)比桃樹(shù)少20%，桃樹(shù)是它們總棵樹(shù)的約55.6%．
故答案為：25，20，55.6．

點(diǎn)評(píng) 此題主要是考查百分?jǐn)?shù)的應(yīng)用．求一個(gè)數(shù)是另一個(gè)數(shù)的百分之幾，用這個(gè)數(shù)除以另一個(gè)數(shù)；求一個(gè)數(shù)比另一個(gè)數(shù)多或少百分之幾，用這兩數(shù)之差除以另一個(gè)數(shù)．