Question

10．甲數(shù)的$\frac{1}{4}$等于乙數(shù)的$\frac{1}{5}$，乙數(shù)比甲數(shù)多25%，甲數(shù)比乙數(shù)少20%．

Answer 1

分析 根據(jù)“甲數(shù)的$\frac{1}{4}$等于乙數(shù)的$\frac{1}{5}$”，先把甲數(shù)看作單位“1”，則乙數(shù)是甲數(shù)的（$\frac{1}{4}$$÷\frac{1}{5}$），再把乙數(shù)看作單位“1”，則甲數(shù)是乙數(shù)的（$\frac{1}{5}$$÷\frac{1}{4}$），進(jìn)一步解答即可．

解答 解：（$\frac{1}{4}$$÷\frac{1}{5}$-1）÷1
=（$\frac{1}{4}$×$\frac{5}{1}$-1）÷1
=$\frac{1}{4}$÷1
=0.25÷1
=0.25
=25%

（1-$\frac{1}{5}$$÷\frac{1}{4}$）÷1
=（1-$\frac{1}{5}$×$\frac{4}{1}$）÷1
=（1-$\frac{4}{5}$）÷1
=$\frac{1}{5}$÷1
=0.2÷1
=0.2
=20%
答：乙數(shù)比甲數(shù)多25%，甲數(shù)比乙數(shù)少20%．
故答案為：25，20．

點(diǎn)評(píng) 解答此題的關(guān)鍵是分清單位“1”的區(qū)別，然后根據(jù)求一個(gè)數(shù)是另一個(gè)數(shù)的百分之幾是多少用除法計(jì)算．