2015 AMC 10A 第 4 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。

4.

Pablo、Sofia 和 Mia 在聚会上得到一些糖果蛋。Pablo 的糖果蛋数量是 Sofia 的三倍,Sofia 的数量是 Mia 的两倍。Pablo 决定把一些糖果蛋给 Sofia 和 Mia,使三人最后数量相同。Pablo 应该把自己糖果蛋的几分之几给 Sofia?

Pablo, Sofia, and Mia got some candy eggs at a party. Pablo had three times as many eggs as Sofia, and Sofia had twice as many eggs as Mia. Pablo decides to give some of his eggs to Sofia and Mia so that all three will have the same number of eggs. What fraction of his eggs should Pablo give to Sofia?

112\dfrac{1}{12}

16\dfrac{1}{6}

14\dfrac{1}{4}

13\dfrac{1}{3}

12\dfrac{1}{2}

答案:B
知识点:比与比例分数
难度评级:1020
解答:

设 Mia 有 mm 个糖果蛋,则 SofiaSofia2m2m 个,PabloPablo6m6m 个。

糖果蛋总数为 三人数量相同时,每人应有 9m÷3=3m9m \div 3 = 3m 个。 m+2m+6m=9m. m + 2m + 6m = 9m.

Sofia 还需要 3m2m=m3m - 2m = m 个糖果蛋,因此 Pablo 应给她自己原有糖果蛋的 m6m=16\dfrac{m}{6m} = \dfrac{1}{6}

所以正确答案是 B

Let mm be the number of candy eggs that Mia had. Then SofiaSofia had 2m2m eggs and PabloPablo had 6m6m eggs.

The total number of eggs is then m+2m+6m=9m. m + 2m + 6m = 9m. For all of them to have the same number of eggs, they each must have 9m÷3=3m9m \div 3 = 3m eggs.

Sofia needs 3m2m=m3m - 2m = m more eggs. This means Pablo must give m6m=16\dfrac{m}{6m} = \dfrac{1}{6} of his eggs to Sofia.

Thus, B is the correct answer.

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