2019 AMC 12B 第 1 题

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所有题目均经美国数学协会(MAA)官方合法授权使用。

1.

Alicia 有两个容器。第一个装了 56\dfrac{5}{6} 容积的水,第二个是空的。她把第一个容器中的水全部倒入第二个容器, 此时第二个容器装了 34\dfrac{3}{4} 容积的水。第一个容器的体积与第二个容器的体积之比是多少?

Alicia had two containers. The first was 56\dfrac{5}{6} full of water and the second was empty. She poured all the water from the first container into the second container, at which point the second container was 34\dfrac{3}{4} full of water. What is the ratio of the volume of the first container to the volume of the second container?

58\dfrac{5}{8}

45\dfrac{4}{5}

78\dfrac{7}{8}

910\dfrac{9}{10}

1112\dfrac{11}{12}

答案:D
知识点:比与比例分数
难度评级:880
解答:

倒水前后水的体积相同,所以 56V1=34V2\dfrac{5}{6}V_1=\dfrac{3}{4}V_2

因此 V1V2=3/45/6=3465=910. \dfrac{V_1}{V_2}=\dfrac{3/4}{5/6}=\dfrac{3}{4}\cdot\dfrac{6}{5}=\dfrac{9}{10}.

所以正确答案是 D

The volume of water is the same before and after, so 56V1=34V2.\dfrac{5}{6}V_1=\dfrac{3}{4}V_2.

Then V1V2=3/45/6=3465=910. \dfrac{V_1}{V_2}=\dfrac{3/4}{5/6}=\dfrac{3}{4}\cdot\dfrac{6}{5}=\dfrac{9}{10}.

Thus, D is the correct answer.

完整试卷

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