第62页 - 课时学案作业本五年级数学

$\frac {8}{15}$

$\frac 34$

$\frac {3}{50}$

$\frac {24}{25}$

$\frac {5}{12}=\frac {10}{24}，$$\frac {3}{8}=\frac {9}{24}$

$\frac {10}{24}>\frac {9}{24}，$$\frac {5}{12}>\frac {3}{8}$

$\frac {7}{15}=\frac {21}{45}，$$\frac {5}{9}=\frac {25}{45}$

$\frac {21}{45}<\frac {25}{45}，$$\frac {7}{15}<\frac {5}{9}$

方法一：$\frac {5}{7}=\frac {25}{35}，$$\frac {3}{5}=\frac {21}{35}$

$\frac {25}{35}>\frac {21}{35}，$$\frac {5}{7}>\frac {3}{5}$

方法二：$\frac 57≈0.71，$$\frac 35=0.6$

$0.72＞0.6，$$\frac {5}{7}>\frac {3}{5}$

$12÷15=\frac 45$

$(20-5)÷20=\frac 34$

$\frac 45＞\frac 34$

答：小军射得准一些。

$\frac 14=\frac {5}{20}，$$\frac 15=\frac {4}{20}，$$\frac {3}{10}=\frac {6}{20}$

$\frac 15＜\frac 14＜\frac {3}{10}$

答：应多进椰蓉面包。

答：这个带分数是$7\frac 89。$

$\frac {13}{84}、$$\frac {25}{168}、$$\frac {9}{56}$

$\frac {755}{756}=1-\frac {1}{756}$

$\frac {84}{85}=1-\frac {1}{85}$

$\frac {1243}{1244}=1-\frac {1}{1244}$

$\frac {16}{17}=1-\frac {1}{17}$

$\frac {1}{17}＞\frac {1}{85}＞\frac {1}{756}＞\frac {1}{1244}$

所以$\frac {16}{17}＜\frac {84}{85}＜\frac {755}{756}＜\frac {1243}{1244}$