Question

油漆工 Paula 原本有刚好够刷 $30$ 间同样大小房间的油漆。不幸的是，在去工作的路上，有三罐油漆从卡车上掉了下来，所以她只剩下够刷 $25$ 间房间的油漆。她刷这 $25$ 间房间用了多少罐油漆？

Paula the painter had just enough paint for $30$ identically sized rooms. Unfortunately, on the way to work, three cans of paint fell off her truck, so she had only enough paint for $25$ rooms. How many cans of paint did she use for the $25$ rooms?

$10$

$12$

$15$

$18$

$25$

答案：C

知识点：比与比例

难度评级：900

小提示：

丢失的 $3$ 罐油漆对应她少刷的 $5$ 间房间。

The $3$ lost cans account for the $5$ rooms she can no longer paint

大提示：

油漆罐数与房间数的比是 $3 : 5$ 。

The ratio of cans to rooms is $3 : 5$

解答：

丢失 $3$ 罐使她少刷 $5$ 间房间，所以 $3$ 罐油漆能刷 $5$ 间房间，每间房需要 $\dfrac{3}{5}$ 罐。

刷 $25$ 间房间需要 $25 \cdot \dfrac{3}{5} = 15$ 罐。

所以正确答案是 C。

Losing $3$ cans cost her $5$ rooms, so $3$ cans paint $5$ rooms and each room needs $\dfrac{3}{5}$ of a can.

For $25$ rooms she used $25 \cdot \dfrac{3}{5} = 15$ cans.

Thus, the correct answer is C.

2009 AMC 12B 第 2 题

答案：C

难度评级：900

小提示：

大提示：

解答：

其他年份的第 2 题