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2. 下面各组数中互为倒数的是$(\quad)$。
A.$0.5$和$2$
B.$\frac{1}{8}$和$\frac{7}{8}$
C.$\frac{4}{3}$和$\frac{1}{3}$
A.$0.5$和$2$
B.$\frac{1}{8}$和$\frac{7}{8}$
C.$\frac{4}{3}$和$\frac{1}{3}$
答案
A
3. 一袋大米$25kg$，第一次用去$\frac{2}{5}$，第二次用去$\frac{2}{5}kg$，还剩$(\quad)kg$。
A.$14\frac{3}{5}$
B.$9$
C.$5$
A.$14\frac{3}{5}$
B.$9$
C.$5$
答案
A
4. 跑完$1500m$，小红用了$\frac{1}{6}$小时，小芳用了$\frac{1}{5}$小时，小丽用了$13$分钟，她们三人中跑得最快的是$(\quad)$。
A.小红
B.小芳
C.小丽
A.小红
B.小芳
C.小丽
答案
A
5. 甲数是乙数的$\frac{1}{5}$，乙数是丙数的$\frac{1}{5}$，甲数是丙数的$(\quad)$。
A.$\frac{1}{5}$
B.$25$倍
C.$\frac{1}{25}$
A.$\frac{1}{5}$
B.$25$倍
C.$\frac{1}{25}$
答案
C
1. 直接写得数。
$0×\frac{6}{7}=$ $\frac{1}{5}÷\frac{3}{5}=$ $\frac{1}{6}×\frac{3}{4}=$ $\frac{2}{3}÷\frac{1}{4}=$ $\frac{6}{7}÷6=$
$1÷\frac{1}{4}=$ $\frac{1}{7}×5=$ $\frac{2}{5}÷4=$ $5÷\frac{5}{4}=$ $24÷\frac{3}{8}=$
$0×\frac{6}{7}=$ $\frac{1}{5}÷\frac{3}{5}=$ $\frac{1}{6}×\frac{3}{4}=$ $\frac{2}{3}÷\frac{1}{4}=$ $\frac{6}{7}÷6=$
$1÷\frac{1}{4}=$ $\frac{1}{7}×5=$ $\frac{2}{5}÷4=$ $5÷\frac{5}{4}=$ $24÷\frac{3}{8}=$
答案
0
$ \frac{1}{3} $
$ \frac{1}{8} $
$ \frac{8}{3} $
$\frac {1}{7}$
4
$ \frac{5}{7} $
$ \frac{1}{10} $
4
64
$ \frac{1}{3} $
$ \frac{1}{8} $
$ \frac{8}{3} $
$\frac {1}{7}$
4
$ \frac{5}{7} $
$ \frac{1}{10} $
4
64
2. 我会化简比。
$96:54$ $\frac{6.4}{0.08}$
$1\frac{2}{7}:0.18$ $12$分钟$:3.5$小时
$96:54$ $\frac{6.4}{0.08}$
$1\frac{2}{7}:0.18$ $12$分钟$:3.5$小时
答案
= 16:9
$=\frac {640}{8}$
=80:1
=9×100:18×7
= 50:7
=12分钟:210分钟
= 2:35
3. 怎样算简便就怎样算。
$\frac{5}{6}×\frac{6}{5}-\frac{9}{10}÷\frac{9}{5}$ $4-\frac{5}{11}-\frac{6}{11}$ $\frac{7}{13}÷6+\frac{1}{6}×\frac{6}{13}-\frac{1}{6}$
$[\frac{5}{3}-(\frac{2}{5}+\frac{3}{4})]÷\frac{31}{4}$ $\frac{1}{18}×\frac{5}{7}+\frac{5}{18}×\frac{17}{7}$ $(\frac{1}{36}÷\frac{1}{4}+\frac{1}{9})÷\frac{5}{6}$
$\frac{5}{6}×\frac{6}{5}-\frac{9}{10}÷\frac{9}{5}$ $4-\frac{5}{11}-\frac{6}{11}$ $\frac{7}{13}÷6+\frac{1}{6}×\frac{6}{13}-\frac{1}{6}$
$[\frac{5}{3}-(\frac{2}{5}+\frac{3}{4})]÷\frac{31}{4}$ $\frac{1}{18}×\frac{5}{7}+\frac{5}{18}×\frac{17}{7}$ $(\frac{1}{36}÷\frac{1}{4}+\frac{1}{9})÷\frac{5}{6}$
答案
$=1-\frac {1}{2}$
$= \frac{1}{2} $
$=4-(\frac {5}{11}+\frac {6}{11})$
= 3
$ =\frac {1}{6}×(\frac {7}{13}+\frac {6}{13}-1)$
=0
$=\frac {31}{60}×\frac {4}{31} $
$=\frac{1}{15} $
$=\frac {5}{18}×(\frac {1}{7}+\frac {17}{7}) $
$=\frac{5}{7} $
$=\frac {2}{9}×\frac {6}{5} $
$=\frac{4}{15} $
$= \frac{1}{2} $
$=4-(\frac {5}{11}+\frac {6}{11})$
= 3
$ =\frac {1}{6}×(\frac {7}{13}+\frac {6}{13}-1)$
=0
$=\frac {31}{60}×\frac {4}{31} $
$=\frac{1}{15} $
$=\frac {5}{18}×(\frac {1}{7}+\frac {17}{7}) $
$=\frac{5}{7} $
$=\frac {2}{9}×\frac {6}{5} $
$=\frac{4}{15} $
