Question

Rachelle 用 $3$ 磅肉为家人做 $8$ 个汉堡。她要为社区野餐做 $24$ 个汉堡，需要多少磅肉？

Rachelle uses $3$ pounds of meat to make $8$ hamburgers for her family. How many pounds of meat does she need to make $24$ hamburgers for a neighborhood picnic?

$6$

$6\dfrac23$

$7\dfrac12$

$8$

$9$

答案：E

知识点：比与比例

难度评级：370

小提示：

从 $8$ 个汉堡按比例放大到 $24$ 个汉堡。

Scale from $8$ hamburgers to $24$ hamburgers.

大提示：

汉堡数量变为三倍，所以肉的数量也变为三倍。

The hamburger count triples, so the meat amount triples.

视频讲解：

Click to load, then click again to play

文字解答：

$8$ 个汉堡是 $24$ 个汉堡的 $\dfrac{1}{3}$ ，所以 $3$ 磅也是所需肉量的 $\dfrac{1}{3}$ 。因此总肉量为 $\dfrac{1}{\dfrac{1}{3}} \cdot 3 = 3\cdot3 = 9$ 。

所以正确答案是 E。

If we have $8$ hamburgers, we have $\dfrac{1}{3}$ of the $24$ hamburgers. This means we have $\dfrac{1}{3}$ of the meat when we have $3$ pounds. The total amount of meat is therefore $\dfrac{1}{\dfrac{1}{3}} \cdot 3 = 3\cdot3 = 9.$

Thus, the answer is E .

2012 AMC 8 第 1 题