Question

（2012?德江縣模擬）把甲隊(duì)人數(shù)的

1

5

調(diào)入乙隊(duì)后兩隊(duì)人數(shù)相等，原來甲隊(duì)人數(shù)比乙隊(duì)（　�。�

• A．多

  1

  10

• B．多

  2

  5

• C．多

  2

  3

Answer 1

分析：將甲隊(duì)人數(shù)當(dāng)做單位“1”，把甲隊(duì)人數(shù)的

1

5

調(diào)入乙隊(duì)后，甲隊(duì)還剩原來的1-

1

5

=

4

5

，此時(shí)兩隊(duì)人數(shù)相等，即此時(shí)乙隊(duì)人數(shù)現(xiàn)在相當(dāng)于甲隊(duì)原來的

4

5

，則乙隊(duì)原來是甲隊(duì)的

4

5

-

1

5

=

3

5

，所以甲隊(duì)人數(shù)比乙隊(duì)多

2

5

÷

3

5

=

2

3

．

解答：解：原來乙隊(duì)是甲隊(duì)的：1-

1

5

-

1

5

=

3

5

，
甲隊(duì)比乙隊(duì)多：
（1-

3

5

）÷

3

5

=

2

5

÷

3

5

，
=

2

3

．
故選：C．

點(diǎn)評(píng)：將甲隊(duì)人數(shù)當(dāng)做單位“1”，根據(jù)分?jǐn)?shù)減法的意義求出乙隊(duì)人數(shù)占甲隊(duì)人數(shù)的分率是完成本題的關(guān)鍵．